Configure Dependabot to automatically detect updates to the actions used in
GitHub Actions (e.g., `actions/checkout`) and create pull requests for them.
For example, `actions/checkout@v4` is likely updatable, as v6 is already available:
9f3b4ff/.github/workflows/main.yml (L15)
This PR enables Dependabot to update such GitHub Actions dependencies.
Updates to outdated actions packages in `.github/workflows` are intentionally not included in this PR,
as they will be updated by the initial Dependabot run as part of verifying its behavior.
Based on experience, checking for updates on a weekly interval should work well.
dd02737463