Force cpu usage on macos-latest runners

[IgorTatarnikov]

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Description

What is this PR

• [x] Bug fix
• [ ] Addition of a new feature
• [ ] Other

Why is this PR needed? Currently, the macos-latest does not have access to a GPU, however, torch.backends.mps.is_available() returns true leading to issues when keras tries to allocate a tensor on the GPU. This leads to errors during testing.

What does this PR do? Forces keras and torch to use CPU when running on the macos-latest runner (identified by GITHUB_ACTIONS env variable and torch.backends.mps.is_available().

How has this PR been tested?

Tested locally and on CI.

Is this a breaking change?

No

Does this PR require an update to the documentation?

No

Checklist:

• [x] The code has been tested locally
• [x] The code has been formatted with pre-commit

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 85.83%. Comparing base (2cf2020) to head (39c4210).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #114 +/- ## ========================================== + Coverage 85.64% 85.83% +0.18% ========================================== Files 16 17 +1 Lines 836 847 +11 ========================================== + Hits 716 727 +11 Misses 120 120 ```

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[adamltyson]

@IgorTatarnikov is this ready for review?

[IgorTatarnikov]

Yes! Forgot to mark is as ready.