Use UDBZ format for macos disk image

[twizmwazin]

This'll hopefully get the macOS bundle size more under control

[twizmwazin]

This does shrink the dmg by 18%, but it adds 8 minutes to the build time to do so, I'm not sure that's a worthwhile tradeoff.

[ltfish]

This does shrink the dmg by 18%, but it adds 8 minutes to the build time to do so, I'm not sure that's a worthwhile tradeoff.

I think it's worthwhile.

[twizmwazin]

I've switched over to using zips for macos.