ci: backport job

.github/workflows/backport.yml

@@ -0,0 +1,20 @@
+name: backport
+
+# backport by issue a label (backport <target branch>) on merged PR 
+
+on:
+  pull_request_target:
+    types: [closed, labeled]
+jobs:
+  backport:
+    permissions:
+      contents: write # so it can comment
+      pull-requests: write # so it can create pull requests
+    name: Backport Pull Request
+    if: github.event.pull_request.merged
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Create backport PRs
+        uses: korthout/backport-action@v2