Bumps [actions/checkout](https://github.com/actions/checkout) from 2.4.0 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/v2.4.0...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>

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1488

Discussed here:
- https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1522#issuecomment-1008381512
- https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1524#issuecomment-1008477510

avoiding common pitfalls that can easily lead to bugs or make code harder to maintain