Update vendor directory

vendor/google.golang.org/protobuf/internal/fieldnum/empty_gen.go

@@ -0,0 +1,10 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Code generated by generate-protos. DO NOT EDIT.
+
+package fieldnum
+
+// Field numbers for google.protobuf.Empty.
+const ()