#12: bumped css-selector requirements

Author: JanDC

composer.json

@@ -13,7 +13,7 @@
   ],
   "require": {
     "php": "^5.5 || ^7",
-    "symfony/css-selector": "^2.7|~3.0",
+    "symfony/css-selector": "^2.7|~3.0|~4.0",
     "twig/twig": "^1.0|^2.0",
     "doctrine/cache": "^1.7"
   },