- Update version to 1.20.4
* Updated rustls to v0.23 with ring backend
* local-redir, server: Better approach to check current platform IP stack
capabilities like Go (IPv4, IPv6, IPv4-mapped-IPv6 supports)
* Explicitly enable dual-stack if listen addresses (server, local_address)
are IPv4-mapped-IPv6, by setting IPV6_V6ONLY=0
* PingBalancer check Firefox portal allowing 200 HTTP status
* Ping Balancer scores replaced standard deviation with median absolute
deviation, which should help focusing less on outlying observations in
latency samples
* local: Allow configuring SOCKS5 UDP_ASSOCIATE address
* ProxyServerStream::from_stream made public
* Fix bugs