go.mod: update github.com/golang/protobuf

Drop use of the MessageType.GoType method.

Change-Id: I50278e54b04556fe6e2830756a5689be1edc9235
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/198997
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
diff --git a/cmd/protoc-gen-go-grpc/testdata/go.mod b/cmd/protoc-gen-go-grpc/testdata/go.mod
index fff7b2b..ca76c7e 100644
--- a/cmd/protoc-gen-go-grpc/testdata/go.mod
+++ b/cmd/protoc-gen-go-grpc/testdata/go.mod
@@ -3,7 +3,7 @@
 go 1.9
 
 require (
-	github.com/golang/protobuf v1.2.1-0.20190828184314-28cdcb54310f
+	github.com/golang/protobuf v1.2.1-0.20191004062209-62f67f1ea9df
 	google.golang.org/grpc v1.19.0
 	google.golang.org/protobuf v1.0.0
 )
diff --git a/cmd/protoc-gen-go/testdata/go.mod b/cmd/protoc-gen-go/testdata/go.mod
index 2f6a8be..e9d06cc 100644
--- a/cmd/protoc-gen-go/testdata/go.mod
+++ b/cmd/protoc-gen-go/testdata/go.mod
@@ -3,7 +3,7 @@
 go 1.9
 
 require (
-	github.com/golang/protobuf v1.2.1-0.20190828184314-28cdcb54310f
+	github.com/golang/protobuf v1.2.1-0.20191004062209-62f67f1ea9df
 	google.golang.org/protobuf v1.0.0
 )
 
diff --git a/go.mod b/go.mod
index f1dc7e9..0be0118 100644
--- a/go.mod
+++ b/go.mod
@@ -3,6 +3,6 @@
 go 1.9
 
 require (
-	github.com/golang/protobuf v1.2.1-0.20190828184314-28cdcb54310f
+	github.com/golang/protobuf v1.2.1-0.20191004062209-62f67f1ea9df
 	github.com/google/go-cmp v0.3.0
 )
diff --git a/go.sum b/go.sum
index e857c88..4067534 100644
--- a/go.sum
+++ b/go.sum
@@ -12,8 +12,8 @@
 github.com/golang/protobuf v1.2.1-0.20190820204156-2da1b93405dd/go.mod h1:x87I3ou7ehf/yR6iQ88MkyDogdxXN04TELJ7HVy7V7I=
 github.com/golang/protobuf v1.2.1-0.20190820213554-ae1d65bc5435 h1:mh1ym3CXIEzWTZlfDucUHHIbroKZ8ri4E3dbxu80las=
 github.com/golang/protobuf v1.2.1-0.20190820213554-ae1d65bc5435/go.mod h1:k7dGkiTZ3rjVDhKSpGt+x1zDzAePJk4jdhoBwIkQgBo=
-github.com/golang/protobuf v1.2.1-0.20190828184314-28cdcb54310f h1:S72Y7P/ygIGdj6ZTtWtBDYKMEHudzFg0KqWXGgQ/U4I=
-github.com/golang/protobuf v1.2.1-0.20190828184314-28cdcb54310f/go.mod h1:o4el5ABfDjqFlwwvAq2OIgAPeNXQYUkhtrjNPXy6T6I=
+github.com/golang/protobuf v1.2.1-0.20191004062209-62f67f1ea9df h1:EXfvyTCV8/aeUp9mwwpgEDbIiiRci9e2PRaV0twjhBM=
+github.com/golang/protobuf v1.2.1-0.20191004062209-62f67f1ea9df/go.mod h1:o4el5ABfDjqFlwwvAq2OIgAPeNXQYUkhtrjNPXy6T6I=
 github.com/google/go-cmp v0.3.0 h1:crn/baboCvb5fXaQ0IJ1SGTsTVrWpDsCWC8EGETZijY=
 github.com/google/go-cmp v0.3.0/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
 google.golang.org/protobuf v0.0.0-20190514172829-e89e6244e0e8/go.mod h1:791zQGC15vDqjpmPRn1uGPu5oHy/Jzw/Q1n5JsgIIcY=