Use google.golang.org/protobuf instead of github.com/golang/protobuf

[chaodaiG]

As stated https://github.com/golang/protobuf#go-support-for-protocol-buffers, that:

This module (github.com/golang/protobuf) contains Go bindings for protocol buffers.

It has been superseded by the google.golang.org/protobuf module, which contains an updated and simplified API, support for protobuf reflection, and many other improvements. We recommend that new code use the google.golang.org/protobuf module.

[timford]

Thanks @chaodaiG . We're probably not going to go out of our way to update, but if we find the opportunity when it makes sense we'll do so.

[chaodaiG]

Thank you