Rebase action: /rebase as comment

Signed-off-by: Andy Scherzinger <info@andy-scherzinger.de>

.github/workflows/rebase.yml

@@ -0,0 +1,18 @@
+on:
+    issue_comment:
+        types: [ created ]
+name: Automatic Rebase
+jobs:
+    rebase:
+        name: Rebase
+        if: github.event.issue.pull_request != '' && contains(github.event.comment.body, '/rebase')
+        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.GITHUB_TOKEN }}