change version to 1.2.1 before releasing
diff --git a/rpc_util.go b/rpc_util.go
index 4b77ca6..28aab0a 100644
--- a/rpc_util.go
+++ b/rpc_util.go
@@ -529,4 +529,4 @@
 const SupportPackageIsVersion4 = true
 
 // Version is the current grpc version.
-const Version = "1.2.2-dev"
+const Version = "1.2.1"