Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 3.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/compare/v2...v3)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

BREAKING CHANGE: Docker support has been removed.
If you were using it, please migrate to [one of the other available options](https://kosmorro.space/cli/download/).

BREAKING CHANGE: on Ubuntu 20.04+, the `texlive-latex-extra` package is needed to generate the PDF output