Don't group protoc-gen-go with other go deps in renovate

[fcanovai]

In #39 renovate is trying to upgrade google.golang.org/grpc/cmd/protoc-gen-go-grpc and google.golang.org/protobuf/cmd/protoc-gen-go from protoc-gen-go-grpc main.go, and a lot of other dependencies. Those two needs to be upgraded, while the others are related to dagger and upgraded with dagger develop. Split the two out of the group, and ignore other deps in renovate.