gRPC migration update

Change-Id: Icdd1a824948fa994cd36bd121c962f5ecf74e3cf
diff --git a/vendor/golang.org/x/net/context/go19.go b/vendor/golang.org/x/net/context/go19.go
index d88bd1d..64d31ec 100644
--- a/vendor/golang.org/x/net/context/go19.go
+++ b/vendor/golang.org/x/net/context/go19.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build go1.9
 // +build go1.9
 
 package context