Add exempt-issue-labels to stale check workflow (opea-project#1861)

Signed-off-by: Sun, Xuehao <xuehao.sun@intel.com>

Author: XuehaoSun

.github/workflows/daily_check_issue_and_pr.yml

@@ -26,3 +26,4 @@ jobs:
           close-pr-message: "This PR was closed because it has been stalled for 7 days with no activity."
           repo-token: ${{ secrets.ACTION_TOKEN }}
           start-date: "2025-03-01T00:00:00Z"
+          exempt-issue-labels: "Backlog"