Update go.sum

go.mod

@@ -112,6 +112,7 @@ require (
 	go4.org v0.0.0-20190313082347-94abd6928b1d // indirect
 	golang.org/x/sync v0.0.0-20190423024810-112230192c58 // indirect
 	golang.org/x/sys v0.0.0-20190626221950-04f50cda93cb
+	google.golang.org/appengine v1.4.0 // indirect
 	gopkg.in/cheggaaa/pb.v1 v1.0.28
 	gotest.tools/gotestsum v0.3.4
 )