Bump actions/checkout from 3 to 4 (#126)

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] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Tobias Knopp <[email protected]>

.github/workflows/ci.yml

@@ -26,7 +26,7 @@ jobs:
  arch:
  - x64
  steps:
- - uses: actions/checkout@v3
+ - uses: actions/checkout@v4
  - uses: julia-actions/setup-julia@v2
  with:
  version: ${{ matrix.version }}
@@ -60,7 +60,7 @@ jobs:
  name: Documentation
  runs-on: ubuntu-latest
  steps:
- - uses: actions/checkout@v3
+ - uses: actions/checkout@v4
  - uses: julia-actions/setup-julia@v2
  with:
  version: '1'