Log Message:
py-channels: updated to 2.1.0

2.1.0:
* Async HTTP Consumers and WebSocket Consumers both gained new functionality
  (groups, subprotocols, and an async HTTP variant)
* URLRouters now allow nesting
* Async login and logout functions for sessions
* Expiry and groups in the in-memory channel layer
* Improved Live Server test case
* More powerful OriginValidator
* Other small changes and fixes in the full release notes.