GitHub Actions updated the latest macos image to macos-14 [1], which made both of our macos build jobs fail. This reverts to macos-12, which should fix CI for the moment. We can then look into migrating to macos-14 explicitly. [1]: https://github.blog/changelog/2024-04-01-macos-14-sonoma-is-generally-available-and-the-latest-macos-runner-image/