Enable HTTP3

[bwbroersma]

$ curl --http3 -sSI https://desec.io | head -n1
HTTP/2 200 

HTTP3 in nginx can be enabled (and HTTPS record set), in nginx:

http3 on;

+ duplicate the listen with a quic instance, see https://nginx.org/en/docs/quic.html#configuration

Then also a HTTPS record can be added to the DNS zone:

desec.io. IN HTTPS  1 . alpn=h2,h3 

---

At internet.nl we needed these changes (and forgot to expose udp in docker).