Add macOS wheel

Not urgent, but this ticket records our discussion about providing hopsy for macOS. Technically, the c++ backend should compile without any large changes on macOS using clang.

In order to automatically provide macOS, linux and windows wheels, we could use cibuildwheel and github actions. This should be quite simple to setup and we should also automatically upload any main-branch builds to pypi.

This issue is likely to be a good fit for our pair-programming.