Re-enable PR-needs-rebase action for glitch-soc (was disabled upstream for forks)

.github/workflows/rebase-needed.yml

@@ -10,7 +10,7 @@ permissions:
 jobs:
   label-rebase-needed:
     runs-on: ubuntu-latest
-    if: github.repository == 'mastodon/mastodon'
+    if: github.repository == 'glitch-soc/mastodon'
 
     concurrency:
       group: ${{ github.workflow }}-${{ github.ref }}