Add HTTP2 support

[crowlKats]

tungstenite should support connecting to a HTTP2 WS server as per https://datatracker.ietf.org/doc/html/rfc8441

[R2-t]

There has been any work on this? I could help implementing it...

[daniel-abramov]

Hey, unfortunately I have not yet been able to find some time to work on this, but if you're willing to work on this, PRs are always welcome 🙂