add mac build

[dogboydog]

-DUSE_SHARED_PIXMAN=on did not work on mac (https://github.com/dogboydog/qaseprite/actions/runs/12449671814/job/34755602201)

[bjorn]

I had opted to only USE_SHARED_ZLIB=on because the other libraries depend on stuff installed via Homebrew, and as such are not available on macOS by default.

I think the only thing we still need on #3 is the -DCMAKE_OSX_ARCHITECTURES='${{ matrix.architectures }}' parameter. Maybe you could add that to the ci-macos branch?

[bjorn]

I think the only thing we still need on #3 is the -DCMAKE_OSX_ARCHITECTURES='${{ matrix.architectures }}' parameter. Maybe you could add that to the ci-macos branch?

I've copied over those lines and this fixed #3. :-)