PMM-7: add stale action (#1072)

* add stale action

* fix newline

* add PR suggestions

Author: idoqo

.github/workflows/stale.yml

@@ -0,0 +1,15 @@
+name: 'Close stale issues and PRs'
+on:
+  schedule:
+    - cron: '30 1 * * MON-FRI' # 1:30 AM every weekday
+
+jobs:
+  stale:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/stale@v9
+        with:
+          stale-issue-message: 'This issue has been marked as stale because it has been open for 120 days without activity. Please remove the stale label or add a comment; otherwise, it will be closed in 7 days.'
+          days-before-stale: 120
+          days-before-close: 7
+          exempt-issue-labels: bug