feat: add automated backport support

.github/automatic_backport_tracks.yaml

@@ -0,0 +1,2 @@
+automatic_backport_tracks:
+  -   track/1.9

.github/workflows/on_pull_request.yaml

@@ -8,6 +8,15 @@ on:
   pull_request:
 
 jobs:
+
+  populate-labels:
+    name: Populate labels
+    if: github.base_ref == 'main' && (github.event.action == 'opened' || github.event.action == 'reopened')
+    uses: canonical/charmed-kubeflow-workflows/.github/workflows/populate-labels.yaml@main
+    secrets: inherit
+    with:
+      track_file_path: ".github/automatic_backport_tracks.yaml"
+      label_prefix: "backport "
   build-charm:
     name: Build charm
     runs-on: ubuntu-24.04

.github/workflows/on_pull_request_closed.yaml

@@ -0,0 +1,18 @@
+name: On Pull Request Closed
+
+on:
+  pull_request_target:
+    types: [closed]
+    branches:
+      - main
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  backport:
+    name: Backport pull request
+    if: github.event.pull_request.merged
+    uses: canonical/charmed-kubeflow-workflows/.github/workflows/backport-pr.yaml@main
+    secrets: inherit