Mergify: set commit message for automerge

Author: bartgol

.mergify.yml

@@ -52,3 +52,10 @@ pull_request_rules:
       actions:
         merge:
           method: merge
+          commit_message: |
+            Merge pull request #{pull_request.number} from #{pull_request.head.ref}
+
+            Automatically merged using mergify
+            PR title: #{pull_request.title}
+            PR author: #{pull_request.user.login}
+            PR labels: #{pull_request.labels}