fix(devops): pin macos runners to macos-12

[mikeshultz]

What I did

So it goes.

Ref: https://github.com/ApeWorX/ape/pull/2020

Checklist

• [ ] Passes all linting checks (pre-commit and CI jobs)
• [ ] New test cases have been added and are passing
• [ ] Documentation has been updated
• [ ] PR title follows Conventional Commit standard (will be automatically included in the changelog)