Update to latest `mach-core` and `mach-sysgpu`, and nominated `zig` version
Currently mach-core has disabled sysgpu until further notice, which we need for stability on macOS. There is also a crash on build with sysgpu enabled on Windows for the version currently used in Pixi.
We will be frozen on this version until sysgpu is reenabled in mach-core.
For now, Windows/Linux users can build and run using zig build run, and macOS users can build and run using zig build run -Duse_sysgpu=true.
Would it be safe to make contributions on the mach-core branch right now?
Sorry for the confusion! That big PR is now merged, and 'main' is safe for contributions. The only thing we should avoid is changing mach-core versions until sysgpu is re-enabled. Once that happens I'll update everything to latest. :)