* Update to the latest Serai Substrate
* Add Protobuf to build dependencies
Docker shouldn't need updating as this should've been added to the image
in
2dbace5b01.
* Get substrate to build
* Correct protoc build step
* Remove the benchmarking code
There's some macro resolution error that isn't apparent. I worked on it
for about half an hour but...
* Remove unnecessary clone
* Correct runtime-benchmarks flag usage