sentinel client should listen for switch-master

[tonyay163]

After a failover, we rely on a retry to pick up the new master. It seems like other client libraries will listen for the switch-master and automatically point to it. This will speed up failover recovery

See https://github.com/redis/go-redis/blob/16b55f9519d46711228a1b81792e971542557ca6/sentinel.go#L1110-L1118

[petyaslavova]

Hi @tonyay163, thank you for bringing this up! We will take a look.