chore: Bump "actions/checkout" to v4 (#16)

Co-authored-by: Christopher Georg <christopher.georg@sr-travel.de>

Author: Chris53897

.github/workflows/ci.yaml

@@ -8,7 +8,7 @@ jobs:
   analyse:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: shivammathur/setup-php@v2
         with:
           php-version: '8.1'
@@ -39,7 +39,7 @@ jobs:
           - php-version: '8.2'
           - php-version: '8.3'
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: shivammathur/setup-php@v2
         with:
           php-version: ${{ matrix.php-version }}