Bump actions/cache from 3 to 4

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

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

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

.github/workflows/phpunit.yml

@@ -54,7 +54,7 @@ jobs:
         composer config cache-dir
         echo "::set-output name=dir::$(composer config cache-dir)"
     - name: composer cache
-      uses: actions/cache@v3
+      uses: actions/cache@v4
       with:
         path: ${{ steps.composer-cache-directory.outputs.dir }}
         key: php-${{ matrix.php-versions }}-composer-${{ hashFiles('**/composer.lock') }}