Align formatting and extensions workflows

Signed-off-by: Hidde Beydals <hello@hidde.co>

.github/workflows/rebase.yaml

@@ -0,0 +1,21 @@
+name: rebase
+
+on:
+  pull_request:
+    types: [ opened ]
+  issue_comment:
+    types: [ created ]
+
+jobs:
+  rebase:
+    if: github.event.issue.pull_request != '' && contains(github.event.comment.body, '/rebase') && (github.event.comment.author_association == 'CONTRIBUTOR' || github.event.comment.author_association == 'MEMBER' || github.event.comment.author_association == 'OWNER')
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout the latest code
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+      - name: Automatic Rebase
+        uses: cirrus-actions/rebase@1.3.1
+        env:
+          GITHUB_TOKEN: ${{ secrets.BOT_GITHUB_TOKEN }}