add ZmqManager to dunder init

socketio/__init__.py

@@ -3,10 +3,11 @@ from .base_manager import BaseManager
 from .pubsub_manager import PubSubManager
 from .kombu_manager import KombuManager
 from .redis_manager import RedisManager
+from .zmq_manager import ZmqManager
 from .server import Server
 from .namespace import Namespace
 
 __version__ = '1.6.2'
 
 __all__ = [__version__, Middleware, Server, BaseManager, PubSubManager,
-           KombuManager, RedisManager, Namespace]
+           KombuManager, RedisManager, ZmqManager, Namespace]