run CI on both types of Mac

[alessandrofelder]

Description

What is this PR

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

Why is this PR needed?

We'd like to run CI on both Intel and Silicon Macs.

What does this PR do?

This PR modifies the workflow file so that test and installation runs smoothly on both Mac architectures.

References

Partial solution to https://github.com/brainglobe/BrainGlobe/issues/63

How has this PR been tested?

CI runs observed.

Is this a breaking change?

No

Does this PR require an update to the documentation?

No

Checklist:

• [n/a] The code has been tested locally
• [n/a] Tests have been added to cover all new functionality (unit & integration)
• [n/a] The documentation has been updated to reflect any changes
• [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 97.99%. Comparing base (70f751e) to head (56fc95b).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #143 +/- ## ======================================= Coverage 97.99% 97.99% ======================================= Files 10 10 Lines 448 448 ======================================= Hits 439 439 Misses 9 9 ```

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