[FEATURE REQUEST] redis sentinel support

[mblaschke]

Describe the solution you'd like
not sure how to use sentinel with go-redis in iris.

connect function seems only to support cluster and standalone redis:

// Connect initializes the redis client.
func (r *GoRedisDriver) Connect(c Config) error {
	if r.Client != nil { // if a custom one was given through SetClient.
		return nil
	}

	if len(c.Clusters) > 0 {
		r.Client = redis.NewClusterClient(r.mergeClusterOptions(c))
	} else {
		r.Client = redis.NewClient(r.mergeClientOptions(c))
	}

	return nil
}