chore: use PHP 8.0 for PHPCS

See phpstan/phpstan-symfony#162

Author: Kocal

.github/workflows/build.yml

@@ -54,7 +54,7 @@ jobs:
         uses: "shivammathur/setup-php@v2"
         with:
           coverage: "none"
-          php-version: "7.4"
+          php-version: "8.0"
 
       - name: "Validate Composer"
         run: "composer validate"