chore(deps): update actions/checkout action to v6 (#72)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/php.yml

@@ -18,7 +18,7 @@ jobs:
 
     name: Test PHP ${{ matrix.php-version }}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Setup PHP Action
         uses: shivammathur/setup-php@v2
         with: