Print diff in cs:check command

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

composer.json

@@ -18,7 +18,7 @@
     },
     "scripts": {
         "cs:fix": "php-cs-fixer fix",
-        "cs:check": "php-cs-fixer fix --dry-run",
+        "cs:check": "php-cs-fixer fix --dry-run --diff",
         "lint": "find . -name \\*.php -not -path './lib/composer/*' -not -path './build/.phan/*' -exec php -l \"{}\" \\;"
     }
 }