Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

* update http2 config due to deprecation

the previous way to let `http2` follow a `listen` was depracated, it
moved to `http2 on;`

* enable quic and http3

I hope the comments are somewhat understandable. if someone can describe
the `reuseport` part more concise, please do.