Merge commit '97e4011c3ce31c6d492d5f103e95a35b6ebdc9bd' into glitch-soc/merge-upstream

Conflicts:
- `config/initializers/content_security_policy.rb`:
  Upstream added some code to add the Identity Provider's sign-in endpoint to
  the `form-action` Content Security Policy directive but our version of the
  file is pretty different.
  Ported the change.

.github/workflows/build-push-pr.yml

@@ -18,7 +18,7 @@ jobs:
     steps:
       # Repository needs to be cloned so `git rev-parse` below works
       - name: Clone repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - id: version_vars
         run: |
           echo mastodon_version_metadata=pr-${{ github.event.pull_request.number }}-$(git rev-parse --short HEAD) >> $GITHUB_OUTPUT