Bump actions/checkout from 5 to 6 (#43)

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ jobs:
         php-version: ['7.4', '8.0', '8.1', '8.2', '8.3', '8.4']
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up PHP ${{ matrix.php-version }}
         uses: shivammathur/setup-php@v2
         with: