[VOL-4290] Voltha go library updates for gRPC migration

Change-Id: I1aa2774beb6b7ed7419bc45aeb53fcae8a8ecda0
diff --git a/vendor/github.com/stretchr/testify/LICENSE b/vendor/github.com/stretchr/testify/LICENSE
index f38ec59..4b0421c 100644
--- a/vendor/github.com/stretchr/testify/LICENSE
+++ b/vendor/github.com/stretchr/testify/LICENSE
@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2012-2018 Mat Ryer and Tyler Bunnell
+Copyright (c) 2012-2020 Mat Ryer, Tyler Bunnell and contributors.
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal