chore: add `fake-ip-ttl` to `dns` section

chore: update sing-tun

action: fix build

chore: update utls to tag version

chore: update dependencies

chore: add `/cache/dns/flush` to restful api

fix: incorrect checking of strings.Split return value

strings.Split will never return a slice of length 0 if sep is not empty, so any code that checks if the return value is of length 0 is incorrect and useless.

chore: more unmap for 4in6 address

chore: update dependencies

chore: update dependencies