Remove dependency on the outdated golang.org/x/net package
As golang.org/x/net is outdated and we don't need to use a context package from it anymore it is replaced with context from standard library. Makefile changed to use proper protoc compiler.
As golang.org/x/net is outdated and we don't need to use a context package from it anymore it is replaced with context from standard library. Makefile changed to use proper protoc compiler.