Support `system.peers_v2`

[mpenick]

It looks like gocql added support for peers_v2 and doesn't fallback if it isn't present in some cases.

apache/cassandra-gocql-driver@8f058c6

[joao-r-reis]

Gocql now does fallback to the old system.peers if system.peers_v2 fails so this is no longer high priority.