ci: lock inactive threads after 30 days

.github/workflows/lock.yml

@@ -0,0 +1,19 @@
+name: Lock threads
+
+on:
+  # Daily
+  schedule:
+    - cron: '0 0 * * *'
+  # Manual trigger
+  workflow_dispatch:
+    inputs:
+
+jobs:
+  lock:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: dessant/lock-threads@v3
+        with:
+          github-token: ${{ github.token }}
+          issue-lock-inactive-days: '30'
+          pr-lock-inactive-days: '30'