Add support to 'nostale' for GitHub Actions

Author: victorhora

.github/workflows/stale.yml

@@ -14,5 +14,6 @@ jobs:
         stale-pr-message: 'This issue is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 5 days'
         stale-issue-label: 'stale'
         stale-pr-label: 'stale'
+        exempt-issue-label: 'nostale'
         days-before-stale: 30
         days-before-close: 5