Fix php version to 8.2 for php-cs-fixer job in CI (#20)

CS-Fixer doesn't support php 8.3 yet

Author: maelanleborgne

.github/workflows/ci.yaml

@@ -55,7 +55,7 @@ jobs:
       - name: Setup PHP
         uses: shivammathur/setup-php@v2
         with:
-          php-version: ${{ matrix.php }}
+          php-version: 8.2
           tools: php-cs-fixer
 
       - name: Run PHP-CS-Fixer