🚑 Fix the way we create RefResolver

Author: tyx

JsonSchemaTools.php

@@ -4,6 +4,7 @@
 
 use JsonSchema\Validator;
 use JsonSchema\RefResolver;
+use JsonSchema\Uri;
 
 /**
  * Used as factory because JsonSchema\Validator and JsonSchema\RefResolver are not stateless
@@ -17,6 +18,8 @@ public function createValidator()
 
     public function createRefResolver()
     {
-        return new RefResolver;
+        return new RefResolver(
+            new Uri\UriRetriever(), new Uri\UriResolver()
+        );
     }
 }