Enable parallel processing in php-cs-fixer config

Author: lkrms

.php-cs-fixer.dist.php

@@ -40,6 +40,7 @@
 
 /** @disregard P1009 */
 return (new PhpCsFixer\Config())
+    ->setParallelConfig(PhpCsFixer\Runner\Parallel\ParallelConfigFactory::detect())
     ->setRules([
         'fully_qualified_strict_types' => true,
         'is_null' => true,