Change version to 1.8.1
diff --git a/rpc_util.go b/rpc_util.go
index 7db8b77..add1eb3 100644
--- a/rpc_util.go
+++ b/rpc_util.go
@@ -510,6 +510,6 @@
 )
 
 // Version is the current grpc version.
-const Version = "1.8.1-dev"
+const Version = "1.8.1"
 
 const grpcUA = "grpc-go/" + Version