Improve websocket communication with Centrifugo

[Evanaellio]

Currently, websocket synchronization is done using Django Channels.
While this is currently working, the only supported protocol is websockets, which can be hard to use when working with mobile devices (websockets will disconnect if the phone's screen turns off).

Instead of Django Channels, it might be interesting to study a migration to Centrifugo, which supports more protocols, including ones that can potentially work when the phone screen is turned off (yet to be ttested).

This could come in handy to be able to implement #40

Useful resource : https://centrifugal.dev/blog/2021/11/04/integrating-with-django-building-chat-application