build(deps): bump actions/checkout from 3 to 4 (#128)

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

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

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/book.yml

@@ -12,7 +12,7 @@ jobs:
     container:
       image: michaelfbryan/mdbook-docker-image
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - run: mdbook build
     - uses: actions/upload-artifact@v3
       with: