chore: add stale workflow to auto-close issues (external-secrets#610)

Signed-off-by: Moritz Johner <[email protected]>

.github/workflows/stale.yml

@@ -0,0 +1,17 @@
+name: 'Close stale issues and PR'
+on:
+ schedule:
+ - cron: '30 1 * * *'
+
+jobs:
+ stale:
+ runs-on: ubuntu-latest
+ steps:
+ - uses: actions/stale@v3
+ with:
+ repo-token: ${{ secrets.GITHUB_TOKEN }}
+ stale-issue-message: 'This issue is stale because it has been open 90 days with no activity. Remove stale label or comment or this will be closed in 30 days.'
+ stale-pr-message: 'This pr is stale because it has been open 90 days with no activity. Remove stale label or comment or this will be closed in 30 days.'
+ close-issue-message: 'This issue was closed because it has been stalled for 30 days with no activity.'
+ days-before-stale: 90
+ days-before-close: 30