CI: Fix Mark Issue Duplicate job (#10220)

Co-authored-by: fisker Cheung <lionkay@gmail.com>

.github/workflows/mark-issue-duplicate.yml

@@ -8,8 +8,9 @@ on:
 jobs:
   mark-duplicate:
     runs-on: ubuntu-latest
+    if: ${{ !github.event.issue.pull_request && startsWith(github.event.comment.body, "Duplicate of ") }}
     steps:
-      - uses: actions-cool/issues-helper@v2.0.0
+      - uses: actions-cool/issues-helper@v2.1.1
         with:
           actions: "mark-duplicate"
           token: ${{ secrets.GITHUB_TOKEN }}