Use redis universal client in token bucket

Updated the client to a UniversalClient, which works for redis pools as well as single redis servers.

tokenbucket.go

@@ -344,7 +344,7 @@ func redisKey(prefix, key string) string {
 // Although depending on a persistence and a cluster configuration some data might be lost in case of a failure
 // resulting in an under-limiting the accesses to the service.
 type TokenBucketRedis struct {
-	cli         *redis.Client
+	cli         redis.UniversalClient
 	prefix      string
 	ttl         time.Duration
 	raceCheck   bool
@@ -358,7 +358,7 @@ type TokenBucketRedis struct {
 // If raceCheck is true and the keys in Redis are modified in between State() and SetState() calls then
 // ErrRaceCondition is returned.
 // This adds an extra overhead since a Lua script has to be executed on the Redis side which locks the entire database.
-func NewTokenBucketRedis(cli *redis.Client, prefix string, ttl time.Duration, raceCheck bool) *TokenBucketRedis {
+func NewTokenBucketRedis(cli redis.UniversalClient, prefix string, ttl time.Duration, raceCheck bool) *TokenBucketRedis {
 	return &TokenBucketRedis{cli: cli, prefix: prefix, ttl: ttl, raceCheck: raceCheck}
 }