GitHub started to show deprecation warnings for all Node.js 16 based Actions:
https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/
In order to resolve this:
- build.yml: Update cache to v4
- labeler.yml:
- Remove the now optional 'repo-token' argument
- Add 'sync-labels' to remove non-actual labels on PR updates
- stale.yml: Remove useless issue permission since we don't have issues enabled