grpc: disable linting

Signed-off-by: Vicent Marti <vmg@strn.cat>

go/vt/servenv/grpc_codec.go

@@ -3,7 +3,10 @@ package servenv
 import (
 	"fmt"
 
-	"github.com/golang/protobuf/proto"
+	// use the original golang/protobuf package we can continue serializing
+	// messages from our dependencies, particularly from etcd
+	"github.com/golang/protobuf/proto" //nolint
+
 	"google.golang.org/grpc/encoding"
 	_ "google.golang.org/grpc/encoding/proto"
 )