DX: Upgrade PHP CS Fixer to one that supports PHP 7.3

Author: keradus

composer.json

@@ -27,7 +27,7 @@
         "symfony/http-kernel": "^3.4 || ^4.0"
     },
     "require-dev": {
-        "friendsofphp/php-cs-fixer": "^2.13",
+        "friendsofphp/php-cs-fixer": "^2.14",
         "symfony/framework-bundle": "^3.4 || ^4.0",
         "symfony/phpunit-bridge": "^3.4 || ^4.1",
         "symfony/twig-bundle": "^3.4 || ^4.0",