feat: add field protocol to setupClusterQueryParams (#2600)

Author: ljun20160606

cluster.go

@@ -217,6 +217,7 @@ func setupClusterConn(u *url.URL, host string, o *ClusterOptions) (*ClusterOptio
 func setupClusterQueryParams(u *url.URL, o *ClusterOptions) (*ClusterOptions, error) {
 	q := queryOptions{q: u.Query()}
 
+	o.Protocol = q.int("protocol")
 	o.ClientName = q.string("client_name")
 	o.MaxRedirects = q.int("max_redirects")
 	o.ReadOnly = q.bool("read_only")

cluster_test.go

@@ -1519,6 +1519,10 @@ var _ = Describe("ClusterClient ParseURL", func() {
 			test: "UseDefault",
 			url:  "redis://localhost:123?conn_max_idle_time=",
 			o:    &redis.ClusterOptions{Addrs: []string{"localhost:123"}, ConnMaxIdleTime: 0},
+		}, {
+			test: "Protocol",
+			url:  "redis://localhost:123?protocol=2",
+			o:    &redis.ClusterOptions{Addrs: []string{"localhost:123"}, Protocol: 2},
 		}, {
 			test: "ClientName",
 			url:  "redis://localhost:123?client_name=cluster_hi",