github actions issues

[electronstudio]

• x86 linux builds break when uploading to pypi with twine, because twine has a dependency on rust! best solution is probably to preinstall twine and/or rust in the docker image
• arm64 images are built both on cirrus and on github. need to decide if there's any reason to keep the cirrus build. might have better rpi compatability? but then could we just use the same container to build on github?
• the 'SDL_SOFT' platform combines a platform and an OpenGL version into one thing which is messy. we will need to separate out into separate variables.