diff --git a/beets/test/helper.py b/beets/test/helper.py
index 4effa47f8..c0d785d6e 100644
--- a/beets/test/helper.py
+++ b/beets/test/helper.py
@@ -675,7 +675,7 @@ class ImportSessionFixture(ImportSession):
     >>> importer.run()
 
     This imports ``/path/to/import`` into `lib`. It skips the first
-    album and imports thesecond one with metadata from the tags. For the
+    album and imports the second one with metadata from the tags. For the
     remaining albums, the metadata from the autotagger will be applied.
     """
 
diff --git a/beets/util/__init__.py b/beets/util/__init__.py
index 32a63b216..ac4e3bc3c 100644
--- a/beets/util/__init__.py
+++ b/beets/util/__init__.py
@@ -1130,7 +1130,10 @@ def get_temp_filename(
     tempdir = get_module_tempdir(module)
     tempdir.mkdir(parents=True, exist_ok=True)
 
-    _, filename = tempfile.mkstemp(dir=tempdir, prefix=prefix, suffix=suffix)
+    descriptor, filename = tempfile.mkstemp(
+        dir=tempdir, prefix=prefix, suffix=suffix
+    )
+    os.close(descriptor)
     return bytestring_path(filename)
 
 
diff --git a/beetsplug/__init__.py b/beetsplug/__init__.py
deleted file mode 100644
index ad573cdb3..000000000
--- a/beetsplug/__init__.py
+++ /dev/null
@@ -1,20 +0,0 @@
-# This file is part of beets.
-# Copyright 2016, Adrian Sampson.
-#
-# Permission is hereby granted, free of charge, to any person obtaining
-# a copy of this software and associated documentation files (the
-# "Software"), to deal in the Software without restriction, including
-# without limitation the rights to use, copy, modify, merge, publish,
-# distribute, sublicense, and/or sell copies of the Software, and to
-# permit persons to whom the Software is furnished to do so, subject to
-# the following conditions:
-#
-# The above copyright notice and this permission notice shall be
-# included in all copies or substantial portions of the Software.
-
-"""A namespace package for beets plugins."""
-
-# Make this a namespace package.
-from pkgutil import extend_path
-
-__path__ = extend_path(__path__, __name__)
diff --git a/docs/changelog.rst b/docs/changelog.rst
index bcb8135b8..feb73bc58 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -22,6 +22,9 @@ New features:
 
 Bug fixes:
 
+* :doc:`plugins/fetchart`: Fix fetchart bug where a tempfile could not be deleted due to never being
+  properly closed.
+  :bug:`5521`
 * :doc:`plugins/lyrics`: LRCLib will fallback to plain lyrics if synced lyrics
   are not found and `synced` flag is set to `yes`.
 * Synchronise files included in the source distribution with what we used to
@@ -74,6 +77,8 @@ Bug fixes:
 For packagers:
 
 * The minimum supported Python version is now 3.9.
+* External plugin developers: ``beetsplug/__init__.py`` file can be removed
+  from your plugin as beets now uses native/implicit namespace package setup.
 
 Other changes:
 
diff --git a/docs/dev/plugins.rst b/docs/dev/plugins.rst
index fa7fa645e..96e69153d 100644
--- a/docs/dev/plugins.rst
+++ b/docs/dev/plugins.rst
@@ -3,47 +3,57 @@
 Writing Plugins
 ---------------
 
-A beets plugin is just a Python module inside the ``beetsplug`` namespace
-package. (Check out this `Stack Overflow question about namespace packages`_ if
-you haven't heard of them.) So, to make one, create a directory called
-``beetsplug`` and put two files in it: one called ``__init__.py`` and one called
-``myawesomeplugin.py`` (but don't actually call it that). Your directory
-structure should look like this::
+A beets plugin is just a Python module or package inside the ``beetsplug``
+namespace package. (Check out `this article`_ and `this Stack Overflow
+question`_ if you haven't heard about namespace packages.) So, to make one,
+create a directory called ``beetsplug`` and add either your plugin module::
 
     beetsplug/
-        __init__.py
         myawesomeplugin.py
 
-.. _Stack Overflow question about namespace packages:
-    https://stackoverflow.com/questions/1675734/how-do-i-create-a-namespace-package-in-python/1676069#1676069
+or your plugin subpackage::
 
-Then, you'll need to put this stuff in ``__init__.py`` to make ``beetsplug`` a
-namespace package::
+    beetsplug/
+        myawesomeplugin/
+            __init__.py
+            myawesomeplugin.py
 
-    from pkgutil import extend_path
-    __path__ = extend_path(__path__, __name__)
+.. attention::
 
-That's all for ``__init__.py``; you can can leave it alone. The meat of your
-plugin goes in ``myawesomeplugin.py``. There, you'll have to import the
-``beets.plugins`` module and define a subclass of the ``BeetsPlugin`` class
-found therein. Here's a skeleton of a plugin file::
+    You do not anymore need to add a ``__init__.py`` file to the ``beetsplug``
+    directory. Python treats your plugin as a namespace package automatically,
+    thus we do not depend on ``pkgutil``-based setup in the ``__init__.py``
+    file anymore.
+
+The meat of your plugin goes in ``myawesomeplugin.py``. There, you'll have to
+import ``BeetsPlugin`` from ``beets.plugins`` and subclass it, for example
+
+.. code-block:: python
 
     from beets.plugins import BeetsPlugin
 
-    class MyPlugin(BeetsPlugin):
+    class MyAwesomePlugin(BeetsPlugin):
         pass
 
 Once you have your ``BeetsPlugin`` subclass, there's a variety of things your
 plugin can do. (Read on!)
 
-To use your new plugin, make sure the directory that contains your
-``beetsplug`` directory is in the Python
-path (using ``PYTHONPATH`` or by installing in a `virtualenv`_, for example).
-Then, as described above, edit your ``config.yaml`` to include
-``plugins: myawesomeplugin`` (substituting the name of the Python module
-containing your plugin).
+To use your new plugin, package your plugin (see how to do this with `poetry`_
+or `setuptools`_, for example) and install it into your ``beets`` virtual
+environment. Then, add your plugin to beets configuration
 
-.. _virtualenv: https://pypi.org/project/virtualenv
+.. code-block:: yaml
+
+    # config.yaml
+    plugins:
+      - myawesomeplugin
+
+and you're good to go!
+
+.. _this article: https://realpython.com/python-namespace-package/#setting-up-some-namespace-packages
+.. _this Stack Overflow question: https://stackoverflow.com/a/27586272/9582674
+.. _poetry: https://python-poetry.org/docs/pyproject/#packages
+.. _setuptools: https://setuptools.pypa.io/en/latest/userguide/package_discovery.html#finding-simple-packages
 
 .. _add_subcommands:
 
@@ -249,13 +259,13 @@ The events currently available are:
   during a ``beet import`` interactive session. Plugins can use this event for
   :ref:`appending choices to the prompt <append_prompt_choices>` by returning a
   list of ``PromptChoices``. Parameters: ``task`` and ``session``.
-  
+
 * `mb_track_extract`: called after the metadata is obtained from
   MusicBrainz. The parameter is a ``dict`` containing the tags retrieved from
   MusicBrainz for a track. Plugins must return a new (potentially empty)
   ``dict`` with additional ``field: value`` pairs, which the autotagger will
   apply to the item, as flexible attributes if ``field`` is not a hardcoded
-  field. Fields already present on the track are overwritten. 
+  field. Fields already present on the track are overwritten.
   Parameter: ``data``
 
 * `mb_album_extract`: Like `mb_track_extract`, but for album tags. Overwrites
diff --git a/docs/faq.rst b/docs/faq.rst
index b740c6503..ac7818ab2 100644
--- a/docs/faq.rst
+++ b/docs/faq.rst
@@ -174,9 +174,8 @@ pages.
 …report a bug in beets?
 -----------------------
 
-We use the `issue tracker <https://github.com/beetbox/beets/issues>`__
-on GitHub. `Enter a new issue <https://github.com/beetbox/beets/issues/new>`__
-there to report a bug. Please follow these guidelines when reporting an issue:
+We use the `issue tracker`_ on GitHub where you can `open a new ticket`_.
+Please follow these guidelines when reporting an issue:
 
 -  Most importantly: if beets is crashing, please `include the
    traceback <https://imgur.com/jacoj>`__. Tracebacks can be more
@@ -206,6 +205,7 @@ If you've never reported a bug before, Mozilla has some well-written
 `general guidelines for good bug
 reports`_.
 
+.. _issue tracker: https://github.com/beetbox/beets/issues
 .. _general guidelines for good bug reports: https://developer.mozilla.org/en-US/docs/Mozilla/QA/Bug_writing_guidelines
 
 
@@ -343,11 +343,11 @@ read the file. You can also use specialized programs for checking file
 integrity---for example, type ``metaflac --list music.flac`` to check
 FLAC files.
 
-If beets still complains about a file that seems to be valid, `file a
-bug <https://github.com/beetbox/beets/issues/new>`__ and we'll look into
-it. There's always a possibility that there's a bug "upstream" in the
-`Mutagen <https://github.com/quodlibet/mutagen>`__ library used by beets,
-in which case we'll forward the bug to that project's tracker.
+If beets still complains about a file that seems to be valid, `open a new
+ticket`_ and we'll look into it. There's always a possibility that there's
+a bug "upstream" in the `Mutagen <https://github.com/quodlibet/mutagen>`__
+library used by beets, in which case we'll forward the bug to that project's
+tracker.
 
 
 .. _importhang:
@@ -398,3 +398,5 @@ try `this Super User answer`_.
 
 .. _this Super User answer: https://superuser.com/a/284361/4569
 .. _pip: https://pip.pypa.io/en/stable/
+.. _open a new ticket:
+   https://github.com/beetbox/beets/issues/new?template=bug-report.md
diff --git a/docs/guides/tagger.rst b/docs/guides/tagger.rst
index 68ad908e8..bf1ecbd8a 100644
--- a/docs/guides/tagger.rst
+++ b/docs/guides/tagger.rst
@@ -76,7 +76,8 @@ all of these limitations.
   Musepack, Windows Media, Opus, and AIFF files are supported. (Do you use
   some other format? Please `file a feature request`_!)
 
-.. _file a feature request: https://github.com/beetbox/beets/issues/new
+.. _file a feature request:
+   https://github.com/beetbox/beets/issues/new?template=feature-request.md
 
 Now that that's out of the way, let's tag some music.
 
diff --git a/setup.cfg b/setup.cfg
index 8e3d7e3b8..ba580f2c9 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -37,3 +37,5 @@ allow_any_generics = false
 # FIXME: Would be better to actually type the libraries (if under our control),
 # or write our own stubs. For now, silence errors
 ignore_missing_imports = true
+namespace_packages = true
+explicit_package_bases = true
diff --git a/test/plugins/lyrics_pages.py b/test/plugins/lyrics_pages.py
index 84c9e2441..2d681e111 100644
--- a/test/plugins/lyrics_pages.py
+++ b/test/plugins/lyrics_pages.py
@@ -456,16 +456,6 @@ lyrics_pages = [
     LyricsPage.make(
         "https://www.musica.com/letras.asp?letra=59862",
         """
-        Lady Madonna, children at your feet
-        Wonder how you manage to make ends meet
-        Who finds the money when you pay the rent?
-        Did you think that money was heaven sent?
-
-        Friday night arrives without a suitcase
-        Sunday morning creeping like a nun
-        Monday's child has learned to tie his bootlace
-        See how they run
-
         Lady Madonna, baby at your breast
         Wonders how you manage to feed the rest
 
diff --git a/test/plugins/test_importadded.py b/test/plugins/test_importadded.py
index d48ec6c46..608afb399 100644
--- a/test/plugins/test_importadded.py
+++ b/test/plugins/test_importadded.py
@@ -57,7 +57,7 @@ class ImportAddedTest(PluginMixin, ImportTestCase):
             os.path.getmtime(mfile.path) for mfile in self.import_media
         )
         self.matcher = AutotagStub().install()
-        self.matcher.macthin = AutotagStub.GOOD
+        self.matcher.matching = AutotagStub.IDENT
         self.importer = self.setup_importer()
         self.importer.add_choice(importer.action.APPLY)
 
diff --git a/test/test_importer.py b/test/test_importer.py
index ad6b837f5..a28b646cf 100644
--- a/test/test_importer.py
+++ b/test/test_importer.py
@@ -440,7 +440,7 @@ class ImportTest(ImportTestCase):
         self.prepare_album_for_import(1)
         self.setup_importer()
         self.matcher = AutotagStub().install()
-        self.matcher.macthin = AutotagStub.GOOD
+        self.matcher.matching = AutotagStub.IDENT
 
     def tearDown(self):
         super().tearDown()