Remove gmusic plugin (#6192)

Sometimes it is time to let go of old things:
This PR removes the old gmusic plugin and all related docs. 

---

The google play music service was shutdown in 2020 and already
deprecated in beets 1.6.0.

beetsplug/gmusic.py

@@ -1,27 +0,0 @@
-# This file is part of beets.
-#
-# 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.
-
-"""Deprecation warning for the removed gmusic plugin."""
-
-from beets.plugins import BeetsPlugin
-
-
-class Gmusic(BeetsPlugin):
-    def __init__(self):
-        super().__init__()
-
-        self._log.warning(
-            "The 'gmusic' plugin has been removed following the"
-            " shutdown of Google Play Music. Remove the plugin"
-            " from your configuration to silence this warning."
-        )

docs/changelog.rst

@@ -75,6 +75,8 @@ Other changes:
   maintainability.
 - :doc:`plugins/bpd`: Raise ImportError instead of ValueError when GStreamer is
   unavailable, enabling ``importorskip`` usage in pytest setup.
+- Finally removed gmusic plugin and all related code/docs as the Google Play
+  Music service was shut down in 2020.
 
 2.5.1 (October 14, 2025)
 ------------------------
@@ -1359,9 +1361,9 @@ There are some fixes in this release:
 
 - Fix a regression in the last release that made the image resizer fail to
   detect older versions of ImageMagick. :bug:`3269`
-- :doc:`/plugins/gmusic`: The ``oauth_file`` config option now supports more
+- ``/plugins/gmusic``: The ``oauth_file`` config option now supports more
   flexible path values, including ``~`` for the home directory. :bug:`3270`
-- :doc:`/plugins/gmusic`: Fix a crash when using version 12.0.0 or later of the
+- ``/plugins/gmusic``: Fix a crash when using version 12.0.0 or later of the
   ``gmusicapi`` module. :bug:`3270`
 - Fix an incompatibility with Python 3.8's AST changes. :bug:`3278`
 
@@ -1412,7 +1414,7 @@ And many improvements to existing plugins:
   singletons. :bug:`3220` :bug:`3219`
 - :doc:`/plugins/play`: The plugin can now emit a UTF-8 BOM, fixing some issues
   with foobar2000 and Winamp. Thanks to :user:`mz2212`. :bug:`2944`
-- :doc:`/plugins/gmusic`:
+- ``/plugins/gmusic``:
 
   - Add a new option to automatically upload to Google Play Music library on
     track import. Thanks to :user:`shuaiscott`.
@@ -1851,7 +1853,7 @@ Here are the new features:
 - :ref:`Date queries <datequery>` can also be *relative*. You can say
   ``added:-1w..`` to match music added in the last week, for example. Thanks to
   :user:`euri10`. :bug:`2598`
-- A new :doc:`/plugins/gmusic` lets you interact with your Google Play Music
+- A new ``/plugins/gmusic`` lets you interact with your Google Play Music
   library. Thanks to :user:`tigranl`. :bug:`2553` :bug:`2586`
 - :doc:`/plugins/replaygain`: We now keep R128 data in separate tags from
   classic ReplayGain data for formats that need it (namely, Ogg Opus). A new

docs/plugins/gmusic.rst

@@ -1,5 +0,0 @@
-Gmusic Plugin
-=============
-
-The ``gmusic`` plugin interfaced beets to Google Play Music. It has been removed
-after the shutdown of this service.

docs/plugins/index.rst

@@ -84,7 +84,6 @@ databases. They share the following configuration options:
     fromfilename
     ftintitle
     fuzzy
-    gmusic
     hook
     ihate
     importadded