Remove/replace macOS 13 runners

[k3DW]

In recent CI runs, the macOS 13 jobs are failing

The macOS-13 based runner images are now retired. For more details, see https://github.com/actions/runner-images/issues/13046.
The macOS-13 based runner images are being deprecated, consider switching to macOS-15 (macos-15-intel) or macOS 15 arm64 (macos-latest) instead. For more details see https://github.com/actions/runner-images/issues/13046

It looks like we do more testing on macOS 13 than we do on 14 or 15, so I don't think we can just remove the two macos-13 lines in the CI script