ci: replace probot with actions workflow

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

.github/stale.yml

@@ -1,19 +0,0 @@
-# Number of days of inactivity before an issue becomes stale
-daysUntilStale: 20
-# Number of days of inactivity before a stale issue is closed
-daysUntilClose: 5
-# Issues with these labels will never be considered stale
-exemptLabels:
-  - pinned
-  - security
-  - 'status: pinned'
-  - 'type: security'
-# Label to use when marking an issue as stale
-staleLabel: 'status: stale'
-# Comment to post when marking an issue as stale. Set to `false` to disable
-markComment: >
-  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.
-# Comment to post when closing a stale issue. Set to `false` to disable
-closeComment: false

.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'