ci: Run cs-fixer on PHP 7.4

Author: mitelg

.github/workflows/check-php-code.yml

@@ -39,7 +39,7 @@ jobs:
             -   name: Setup PHP
                 uses: shivammathur/setup-php@v2
                 with:
-                    php-version: '8.1'
+                    php-version: '7.4'
 
             -   name: Cache CS-Fixer
                 uses: actions/cache@v4