Explicitly set requiresMainQueueSetup

Fixes warning on startup:

> Module RCTJPushModule requires main queue setup since it overrides `init` but doesn't implement `requiresMainQueueSetup. In a future release React Native will default to initializing all native modules on a background thread unless explicitly opted-out of.

Author: messense

ios/RCTJPushModule/RCTJPushModule.m

@@ -227,6 +227,10 @@ - (dispatch_queue_t)methodQueue
   return dispatch_get_main_queue();
 }
 
++ (BOOL)requiresMainQueueSetup {
+    return YES;
+}
+
 - (void)didRegistRemoteNotification:(NSString *)token {
   [self.bridge.eventDispatcher sendAppEventWithName:@"didRegisterToken"
                                                body:token];