fix: ZeroMQ broker

[raidzin]

Description

I removed socket.connect because it's not needed for bind, as bind is used for connecting. And I added unbind for broker shutdown.

We can see it in this sources
https://github.com/zeromq/pyzmq/blob/b184fed8b6525da5d9234b470800af9a72565b1c/zmq/sugar/socket.py#L270-L289

Closing

fixes #401

[s3rius]

MyPy is complaining about the code. Can you fix it's error?

[raidzin]

@s3rius maybe we should change the zeromq architecture? Now the worker is connecting to the publisher, and I suggest that the worker make a bind and the others connect to it. This will allow us to send tasks from multiple processes. For example, from a scheduler and a web service

Reference implementaion:
https://gist.github.com/raidzin/2dac71b9f6e325c41138cc18334a7dbc

[s3rius]

I was thinking about active architecture in the past. I guess it does make sense to go with your solution. However it limits ZMQ brokers to only be used with a single worker instance all the time. Because otherwise they will be fighting for ports.