HTTP/3 support

[pablodiegoss]

Hey!
On the readme we have:

Have a single, correct HTTP implementation, supporting versions 1, 2 (and eventually 3)

After looking through some HTTP servers for python, specifically: Uvicorn, Gunicorn, Granian, Daphne and Hypercorn. Only Hypercorn has an http3 optional extra to offer a QUIC bind, however it still seems experimental and not really well documented.

Any roadmap/news/updates on HTTP/3 support by Granian?

[gi0baro]

#550