I installed the latest toolchain according to:
https://grpc.io/docs/languages/go/quickstart/
I updated the protoc command line arguments in Makefile based on
that quickstart guide, then I ran: make update-grpc
This has set the tool version (which you can see at the top of
any .pb.go file) to:
protoc-gen-go v1.25.0
protoc v3.14.0