Fixes #176

[BradyPlanden]

This PR downgrades faer to 0.21.9 with an aligned faer-trait version. In addition, a macos-13 x86 runner is added to the Github CI.

[mhovd]

In #182, I am suggesting bumping faer, rather than downgrading it.

In very good news, faer is back in active development, but has moved from GitHub to Codeberg.

Could you check if the latest version solves the performance regression?

[BradyPlanden]

Thanks @mhovd — yes unfortunately this patch won't solve the problem; however, the most recent release of private-gemm-x86 does. I'm going to update this PR so the macOS Intel support is added to the CI and we can aim to merge it post #182.

[martinjrobins]

@BradyPlanden, now that #182 is merged are you happy to finish this off?

[BradyPlanden]

Brill, yep I'll take another look at this