h3 header to use https_redirection_port

[akostadinov]

This is a follow-up to #178

rpxy listens to port 8443 but firewall forwards 443 to it.

When running a HTTP3 check with https://www.http3check.net I see:

HTTP/1.1 200 OK
x-powered-by: Express
content-type: text/html; charset=utf-8
cache-control: no-store
content-length: 6033
etag: "1791-mYZsXQnlnZvRokIH6Nbx+zvQQPc"
date: Thu, 19 Sep 2024 21:25:18 GMT
server: rpxy
alt-svc: h3=":8443"; ma=3600

And it complains that

Server does not advertise supported HTTP/3 or QUIC version on the same port.

My understanding is that HTTP3 should always be on the same port as HTTP1/2.

[junkurihara]

Thanks! It is a nice catch. I actually missed it.