stale-issues.yml: update to match main configuration

Author: BrewTestBot

.github/workflows/stale-issues.yml

@@ -17,6 +17,10 @@ permissions:
   issues: write
   pull-requests: write
 
+defaults:
+  run:
+    shell: bash -xeuo pipefail {0}
+
 concurrency:
   group: stale-issues
   cancel-in-progress: ${{ github.event_name != 'issue_comment' }}