chore: add backport github action (#9835)

.github/workflows/backport.yaml

@@ -0,0 +1,45 @@
+name: backport
+on:
+  pull_request_target:
+    types:
+      - closed
+      - labeled
+
+jobs:
+  backport_and_merge:
+    runs-on: ubuntu-latest
+    # Only react to merged PRs for security reasons.
+    # See https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#pull_request_target.
+    permissions:
+      contents: write
+      pull-requests: write
+    if: |
+      github.event.pull_request.merged && (
+        github.event.action == 'closed' || (
+          github.event.action == 'labeled' && contains(github.event.label.name, 'backport')
+        )
+      )
+    steps:
+      - name: backport PR
+        uses: tibdex/backport@v2
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          title_template: "[AUTO-BACKPORT <%= number %>] <%= title %>"
+
+      - name: wait-for-checks
+        uses: poseidon/[email protected]
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: merge backported PR
+        id: merge_backport_pr
+        if: success()
+        run: |
+            PR_NUMBER=$(gh pr list --repo ${{ github.repository }} --search "[AUTO-BACKPORT ${{ github.event.pull_request.number }}]" --json number --jq '.[0].number')
+            if [ -n "$PR_NUMBER" ]; then
+              gh pr merge $PR_NUMBER --merge --repo ${{ github.repository }} --admin -t "Auto-merged backport PR."
+            else
+              echo "No backport PR found to merge."
+            fi
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}