Update backport.yml

Author: jonathanlukas

.github/workflows/backport.yml

@@ -1,17 +1,40 @@
-name: Backport merged pull request
+name: Backport labeled merged pull requests
 on:
-  pull_request_target:
+  pull_request:
     types: [closed]
-permissions:
-  contents: write # so it can comment
-  pull-requests: write # so it can create pull requests
+  issue_comment:
+    types: [created]
+
 jobs:
   backport:
-    name: Backport pull request
+    name: Create backport PRs
     runs-on: ubuntu-latest
-    # Don't run on closed unmerged pull requests
-    if: github.event.pull_request.merged
+    # Only run when pull request is merged
+    # or when a comment starting with `/backport` is created by someone other than the
+    # https://github.com/backport-action bot user (user id: 97796249). Note that if you use your
+    # own PAT as `github_token`, that you should replace this id with yours.
+    if: >
+      (
+        github.event_name == 'pull_request' &&
+        github.event.pull_request.merged
+      ) || (
+        github.event_name == 'issue_comment' &&
+        github.event.issue.pull_request &&
+        startsWith(github.event.comment.body, '/backport')
+      )
     steps:
       - uses: actions/checkout@v4
-      - name: Create backport pull requests
+      - name: Create backport PRs
         uses: korthout/backport-action@v3
+        with:
+          pull_description: |-
+            # Description
+            Backport of #${pull_number} to `${target_branch}`.
+
+            relates to ${issue_refs}
+
+          add_author_as_assignee: true
+          experimental: >
+            {
+              "conflict_resolution": "draft_commit_conflicts"
+            }