Dependabot for GitHub Actions: one grouped weekly PR clears the Node 20 checkout warning

The annotation 'Node.js 20 is deprecated... actions/checkout@v4' on GitHub Actions runs means the action major still targets Node 20. To keep actions current without a PR per action, add .github/dependabot.yml with version: 2, package-ecosystem: github-actions, directory: / (Dependabot finds .github/workflows from the root), schedule.interval: weekly, and groups: { actions: { patterns: ['*'] } }, so every action bump arrives as one PR. Leave out npm if you only want Actions; the bun lockfile would need its own package-ecosystem entry. Run Prettier on the new YAML before committing if CI runs prettier --check ..