flask-uwsgi-websocket middlewares violate PEP-333

[ergoithz]

This module is not WSGI compliant. PEP-333 rules start_response callable must be called before wsgi app returns (or starts yielding), and here it isn't for websocket requests, which could make other wsgi middlewares (or any compliant wsgi server) to raise.

https://github.com/zeekay/flask-uwsgi-websocket/blob/d0264d220d570a37100ef01be10a0f01fef1e9df/flask_uwsgi_websocket/websocket.py#L74-L75