[chore] Remove deprecated macos-12 runner, Add macos-15 runner

[sincejune]

Description

ref: actions/runner-images#10721

Link to tracking issue

n/a

Testing

n/a

Documentation

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[mowies]

This is kinda confusing. Why are you building with 14 and 15 but then only uploading 14 and then using that on 13 only?

[mowies]

@atoulme or somebody else with permissions, could you please add the "run darwin" label to run the MacOS unit tests?

[sincejune]

This is kinda confusing. Why are you building with 14 and 15 but then only uploading 14 and then using that on 13 only?

The original workflow copies artifacts from versions 14 to 12 and 13 to verify that the built binary works correctly in older versions. I've added macOS-15 to ensure tests pass on this version, while only uploading artifacts for version 14 to confirm that the legacy workflow remains functional.

There are some hard-coded elements in the Makefile related to the tests in this workflow. I haven't spent more time on this because I'm uncertain if the workflow makes sense, as my main objective with this PR is to resolve the hanging job issue on the main branch.

[mowies]

ok thanks for the explainer. anyways, i think something needs to be changed since macos-13 is x86 and macos-{14,15} is ARM based so I'm not sure if that will work. But nothing is certain until the unit tests are triggered :)

[songy23]

LGTM pending the darwin tests

[mowies]

if it works, it works i guess :D