enable parallelization in php-cs-fixer config

.php-cs-fixer.dist.php

@@ -27,6 +27,7 @@ $config
     ->setRiskyAllowed(true)
     ->setCacheFile('.cache/php-cs-fixer.cache')
     ->setUsingCache(true)
+    ->setParallelConfig(PhpCsFixer\Runner\Parallel\ParallelConfigFactory::detect())
 ;
 
 $rules = $config->getRules();