Update to stable reactphp/event-loop v1.2.0

Author: clue

composer.json

@@ -28,7 +28,7 @@
     "require": {
         "php": ">=5.3.0",
         "react/cache": "^1.0 || ^0.6 || ^0.5",
-        "react/event-loop": "dev-master#78f7f43 as 1.2.0",
+        "react/event-loop": "^1.2",
         "react/promise": "^3.0 || ^2.7 || ^1.2.1",
         "react/promise-timer": "^1.2"
     },