This happens to use C++20 coroutines because I'm lazy. It can
equivalently be written without.
I reworded measure.sh to use cmake instead of zig build. Again, I'm lazy
and don't wish to learn zig build today.
The flake had dependency issues
- for one, the beast archive references in cpp/build.zig.zon is gone;
- secondly the upstream zig flake does not have zig 12.0 ¯\_(ツ)_/¯
Luckily that's in Nixpkgs, so I switched to nixpkgs-unstable.
- I also added a `liburing` dependency to the devShell. This was to
test with uring, but it didn't produce better results
