MacOS builds costs 10x regular builds!

Our MacOS build takes on average 90 seconds.

However these OS builds are charged out at 10x regular minutes, meaning our 90 second build is charged at 15 minutes of build time. This chews through our monthly free build allowance in record time.

For the time being, I've manually disabled that GitHub action.

Whether we re-introduce this OS build is up for debate, so... discuss!