Add stale workflow

Author: rawilk

.github/workflows/stale.yml

@@ -0,0 +1,23 @@
+name: "Close stale issues"
+on:
+    schedule:
+        -   cron: "23 12 * * *"
+
+jobs:
+    stale:
+        runs-on: ubuntu-latest
+        permissions:
+            issues: write
+            pull-requests: write
+
+        steps:
+            -   uses: actions/stale@v5
+                with:
+                    repo-token: ${{ secrets.GITHUB_TOKEN }}
+                    stale-issue-message: "This issue is stale because it has been open 21 days with no activity. Remove stale label or comment or this will be closed in 7 days."
+                    stale-issue-label: "stale"
+                    stale-pr-message: "This PR is stale because it has been open for 21 days with no activity. Remove stale label or comment or this will be closed in 7 days."
+                    stale-pr-label: "stale"
+                    exempt-issue-labels: "enhancement,help wanted"
+                    days-before-stale: 21
+                    days-before-close: 7