Add supported platforms to the build workflow for GitHub Actions
For Pyxel 1.8.0, I've updated the build.yml to build Python wheels for each platform automatically:
https://github.com/kitao/pyxel/blob/main/.github/workflows/build.yml

But for now it only supports x86_64 Windows, x86_64 Linux, aarch64 Mac and x86_64 Mac.

I would like to support other platforms such as i686 Windows and aarch64 Linux, but that would require cross-compiling for Rust-SDL2 (references SDL2) and PyO3 (references Python) and I haven't been able to do that yet.

I look forward to any information or advice on how to do that.