Update actions/checkout to version 5 in test matrix workflow

Author: cklei-carly

.github/workflows/test-matrix.yml

@@ -22,7 +22,7 @@ jobs:
     name: PHP ${{ matrix.php }} - Laravel ${{ matrix.laravel }}
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - name: Setup PHP
         uses: shivammathur/setup-php@v2