Add more

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

.github/workflows/backport.yml

@@ -42,7 +42,7 @@ jobs:
 
       - name: Label new backport PR with backport-automerge label
         run: |
-          PR_BRANCH=backport/backport-<%= number %>-to-<%= base %>
+          PR_BRANCH=backport/backport-${{ github.event.pull_request.number }}-to-${{ github.event.pull_request.base.ref }}
           PR_NUMBER=`gh pr list -R opensearch-project/documentation-website --json "number,headRefName" --state open | jq -r ".[] | select(.headRefName == \"$PR_BRANCH\") | .number"`
           echo "Update Backport PR #$PR_NUMBER on branch $PR_BRANCH with backport-automerge label"
           gh issue edit -R opensearch-project/documentation-website $PR_NUMBER --add-label backport-automerge