Avoid macos-latest Python version compatibility issues in GitHub Actions runner images

[d33bs]

Description

This PR addresses #195, enabling MacOS testing to take place. Based on a recent successful job run, I believe this is a major version jump from macos-12 to macos-13 in an effort to keep the declarative nature of this "more protected" from deprecations as they occur (for the time being).

If all looks good here, I plan to create an issue which helps us remember to update the MacOS version specification to a more compatible version when able or desired.

Closes #195
Required for #194 and other PR's in order to resolve GH Actions failures.

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• Bug fix (fixes an issue).
• Enhancement (adds functionality).
• Breaking change (fix or feature that would cause existing functionality to not work as expected).
• This change requires a documentation update.

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[d33bs]

Thank you @gwaybio ! Merging this in.