ci: replace probot with actions workflow

Probot is basically discontinued, even though it's not 100% clear...

.github/workflows/stale.yml

@@ -0,0 +1,26 @@
+name: 'Close stale issues and PR'
+on:
+ schedule:
+ - cron: '00 5 * * *'
+ workflow_dispatch:
+
+jobs:
+ stale:
+ runs-on: ubuntu-latest
+ steps:
+ - uses: actions/stale@v5
+ with:
+ days-before-stale: 20
+ days-before-close: 5
+ stale-issue-message: >
+ This issue has been automatically marked as stale because it has not had
+ recent activity. It will be closed if no further activity occurs. Thank you
+ for your contributions.
+ stale-pr-message: >
+ This PR has been automatically marked as stale because it has not had
+ recent activity. It will be closed if no further activity occurs. Thank you
+ for your contributions.
+ stale-issue-label: 'status: stale'
+ stale-pr-label: 'status: stale'
+ exempt-issue-labels: 'pinned,security,status: pinned,type: security'
+ exempt-pr-labels: 'pinned,security,status: pinned,type: security'