Updated React dependencies to the latest ones

Author: lordthorzonus

composer.json

@@ -4,8 +4,8 @@
     "description": "Port of Facebook's dataloader to PHP",
     "keywords": ["batch loading", "dataloader", "graphql"],
     "require": {
-        "react/promise": "^2.5",
-        "react/event-loop": "^0.4.2",
+        "react/promise": "^2.7.1",
+        "react/event-loop": "^1.1.0",
         "php": "^7.3.0"
     },
     "require-dev" : {