Add rebase slash command to CI

Author: stefanprodan

.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'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout the latest code
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+      - name: Automatic Rebase
+        uses: cirrus-actions/[email protected]
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}