Update phpstan.yml

Author: vmcj

.github/workflows/phpstan.yml

@@ -22,6 +22,7 @@ jobs:
           php_extensions: gd intl mysqli pcntl zip
           autoload_file: webapp/vendor/autoload.php
           version: composer
+          level: 8
       - uses: actions/upload-artifact@v4
         if: always()
         with: