Bump actions/checkout from 4.1.7 to 4.2.1

Bumps [actions/checkout](https://github.com/actions/checkout) from 4.1.7 to 4.2.1.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@692973e...eef6144)

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

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/docker.yml

@@ -18,7 +18,7 @@ jobs:
       composer_version: "2.7.7"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
+      - uses: actions/checkout@eef61447b9ff4aafe5dcd4e0bbf5d482be7e7871 # v4.2.1
 
       - name: Build the base image
         uses: tweedegolf/build-container-image@main