add github action to clear stale PRs (jup-ag#1529)

.github/workflows/clear-stale-PRs.yml

@@ -0,0 +1,27 @@
+name: clear-stale-PRs
+
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: "0 0 * * *" # UTC Midnight everyday
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+        - name: Close Stale Issues
+        - uses: actions/[email protected]
+        with:
+            repo-token: ${{ secrets.PAT }}
+            # ====== for pr
+            exempt-pr-labels: pinned,security,good-first-issue,in-progress
+
+            days-before-pr-stale: 21
+            stale-pr-message: |
+              This pull request has been automatically marked as stale because it
+              has not had recent activity. It will be closed if no further activity
+              occurs - please feel free to re-open when your project has more traction.
+            days-before-pr-close: 7
+            close-pr-message: |
+              This pull request has not seen any activity since it was marked stale.
+              Closing.