chore: PHPStan: use PHP version from the matrix

Author: alexislefebvre

.github/workflows/code-quality.yaml

@@ -78,7 +78,7 @@ jobs:
             -   name: Setup PHP
                 uses: shivammathur/setup-php@v2
                 with:
-                    php-version: '8.1'
+                    php-version: ${{ matrix.php-version }}
                     tools: flex
 
             - name: Install root dependencies