Get macos-12+, including osx-arm64 (i.e. macos-latest) runners working in CI

[IAlibay]

Follow-up from https://github.com/OpenFreeEnergy/openfe/pull/841#pullrequestreview-2022068366

[IAlibay]

Overview of issue

• macos-13 (x86_64) is not compatible with the current conda-forge deployments of AT22 or AT23. The wheels will get picked up and installed, but SQM will fail
• macos-14 (osx-arm64) does not have compatible AmberTools wheels

TODO:

• [ ] unpin openfe CI
• [ ] unpin gufe CI
• [ ] unpin ExampleNotebooks CI
• [ ] ...