chore(deps): update actions/checkout action to v4 (#325)

* chore(deps): update actions/checkout action to v4

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>
Co-authored-by: danieljbruce <danieljbruce@users.noreply.github.com>