It doesn't work at all, because we're missing something in the net code
to do with endian conversions. I haven't investigated, yet, but at least
now we have a failing test that can be investigated.
Also moved to cmake 3.5 at minimum. CMake will stop supporting lower
versions than that, soon.
Also moved to C11 from C99 to get `static_assert`.
Also made a network ERROR into a WARNING. It triggers on FreeBSD.
We can't run this on pull requests because it needs access to the
`SONAR_TOKEN` secret. Perhaps in the future we can make it a
`pull_request_target` workflow, but then we can't use cmake to initialise
the environment, meaning we need to specify the inputs manually.
