Create stale.yml

Author: Andrew Mikofalvy

Diff for: .github/workflows/stale.yml

@@ -0,0 +1,15 @@
+name: "Prune stale PRs"
+on:
+  schedule:
+  - cron: "25 9 * * *"
+
+jobs:
+  stale:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/stale@v3
+      with:
+        repo-token: ${{ secrets.GITHUB_TOKEN }}
+        stale-pr-message: 'This PR is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 7 days'
+        days-before-stale: 30
+        days-before-close: 7