Use uuid.v4 instead of v1

v1 is based on timestamp, and gives same uuid when methods/subscriptions are called at the same time.

src/RealTimeAPI.ts

@@ -4,7 +4,7 @@
 
 import { Observable } from "rxjs";
 import { WebSocketSubject } from 'rxjs/observable/dom/WebSocketSubject';
-import { v1 as uuid } from "uuid";
+import { v4 as uuid } from "uuid";
 import { SHA256 } from "crypto-js";
 
 export class RealTimeAPI {
@@ -214,4 +214,4 @@ export class RealTimeAPI {
         );
         return subscription;
     }
-}
+}