Add backport tool

.github/workflows/backport.yml

@@ -0,0 +1,46 @@
+name: Backport
+
+on:
+  pull_request_target:
+    types:
+      - closed
+      - labeled
+
+permissions:
+  pull-requests: write
+
+jobs:
+  backport:
+    name: Backport
+    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.
+    if: |
+      github.event.pull_request.merged == true
+      && contains(
+           join(github.event.pull_request.labels.*.name, '---'),
+           'backport'
+         )
+      && (
+        (github.event.action == 'labeled' && startsWith(github.event.label.name, 'backport')) ||
+          (github.event.action == 'closed')
+      )
+    steps:
+      - name: Generate token
+        id: generate_token
+        uses: actions/create-github-app-token@v2
+        with:
+          app-id: ${{ vars.ALCHEMY_BOT_APP_ID }}
+          private-key: ${{ secrets.ALCHEMY_BOT_APP_PRIVATE_KEY }}
+      - name: Backport pull request
+        uses: sorenlouv/[email protected]
+        with:
+          github_token: ${{ steps.generate_token.outputs.token }}
+          auto_backport_label_prefix: backport-to-
+          add_original_reviewers: true
+      - name: Info log
+        if: ${{ success() }}
+        run: cat ~/.backport/backport.info.log
+      - name: Debug log
+        if: ${{ failure() }}
+        run: cat ~/.backport/backport.debug.log