ci: close stale issues (#216)

Author: john-u

.github/workflows/stale.yaml

@@ -0,0 +1,17 @@
+name: Close stale issues
+
+on:
+  schedule:
+    - cron: "30 1 * * *"
+
+permissions:
+  issues: write
+
+jobs:
+  stale:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/stale@v4
+        with:
+          stale-issue-message: "This issue is stale because it has been open 60 days with no activity. Remove stale label or comment or this will be closed in 7 days."
+          exempt-issue-labels: "reviewed"