Add IPv6 support

[r-a303931]

There was an issue with jj-rs in WRCCDC invitational 2 where it wasn't able to see a service bound on '::', the IPv6 anycast address. In particular, it was gitea on port 3000

jj-rs has this fixed in: luccdc/jj-rs@c0e0d57

Services bound to the IPv6 anycast address can be accessed over an IPv4 address using IPv4 only