Bump snowflake/go-webrtc for trac 21312
Please see the attached.
Incidentally, this should also fix,
https://trac.torproject.org/projects/tor/ticket/24203#comment:11
However, note that this now means there won't be a `snowflake.log` anymore, unless we provide a path to `-log` in the `torrc-defaults-appendix`
issue