Bump actions/checkout from 3.6.0 to 4.0.0 (#43)

Bumps [actions/checkout](https://github.com/actions/checkout) from 3.6.0 to 4.0.0.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3.6.0...v4.0.0)

---
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/tests.yml

@@ -11,7 +11,7 @@ jobs:
                 os: [ubuntu-latest, windows-latest]
                 dependency-version: [lowest, highest]
         steps:
-            - uses: actions/checkout@v3.6.0
+            - uses: actions/checkout@v4.0.0
 
             - name: Configure PHP
               uses: shivammathur/setup-php@v2