Update symfony support to 4.2

Author: zys-gd

composer.json

@@ -19,7 +19,7 @@
 
   "require": {
     "php": ">=5.4.0",
-    "symfony/framework-bundle": "2.3 - 4.1",
+    "symfony/framework-bundle": "2.3 - 4.2",
     "doctrine/orm": "~2.3",
     "twig/twig": "~1.5|~2.0"
   },