Add prevent condition due to SvanBoxel/delete-merged-branch#204 issues

Signed-off-by: Peter Zhu <[email protected]>

Author: peterzhuamazon

Diff for: .github/workflows/delete_backport_branch.yml

@@ -7,7 +7,12 @@ on:
 jobs:
   delete-branch:
     runs-on: ubuntu-latest
-    if: startsWith(github.event.pull_request.head.repo.full_name, 'opensearch-project/documentation-website')
+    if: |
+      startsWith(github.event.pull_request.head.repo.full_name, 'opensearch-project/documentation-website') &&
+      startsWith(! github.event.pull_request.head.ref, 'main') &&
+      startsWith(! github.event.pull_request.head.ref, '1.') &&
+      startsWith(! github.event.pull_request.head.ref, '2.') &&
+      startsWith(! github.event.pull_request.head.ref, 'version/')
     steps:
       - name: Echo remove branch
         run: echo Removing ${{github.event.pull_request.head.ref}}