chore(ci): add stale bot (#5700)

Signed-off-by: Ettore Di Giacinto <mudler@users.noreply.github.com>

.github/workflows/stalebot.yml

@@ -0,0 +1,25 @@
+name: 'Close stale issues and PRs'
+permissions:
+  issues: write
+  pull-requests: write
+on:
+  schedule:
+    - cron: '30 1 * * *'
+
+jobs:
+  stale:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/stale@5bef64f19d7facfb25b37b414482c7164d639639 # v9
+        with:
+          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 5 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 10 days.'
+          close-issue-message: 'This issue was closed because it has been stalled for 5 days with no activity.'
+          close-pr-message: 'This PR was closed because it has been stalled for 10 days with no activity.'
+          days-before-issue-stale: 90
+          days-before-pr-stale: 90
+          days-before-issue-close: 5
+          days-before-pr-close: 10
+          exempt-pr-labels: 'enhancement,bug'
+          exempt-pr-issues: 'enhancement,bug'
+          only-labels: 'unconfirmed'