Bump webonyx/graphql-php version

Author: Jeremiah VALERIE

composer.json

@@ -33,7 +33,7 @@
     "guzzlehttp/promises": "^1.3.0",
     "phpunit/phpunit": "^4.1|^5.1",
     "react/promise": "^2.5.0",
-    "webonyx/graphql-php": "^0.9.14"
+    "webonyx/graphql-php": "^0.11.0"
   },
   "suggest": {
     "guzzlehttp/promises": "To use with Guzzle promise",