Update onpr_automerge.yaml

.github/workflows/onpr_automerge.yaml

@@ -3,19 +3,11 @@
 ---
 name: automerge
 on:
-  pull_request:
-    types:
-      - labeled
-      - unlabeled
-      - synchronize
-      - opened
-      - edited
-      - ready_for_review
-      - reopened
-      - unlocked
   pull_request_review:
     types:
       - submitted
+  issue_comment:
+    types: created
   check_suite:
     types:
       - completed