Use default resource class for macos builds on CircleCi

[randomir]

Support for macos.x86.medium.gen2 is soon to be dropped.

See: https://discuss.circleci.com/t/macos-intel-support-deprecation-in-january-2024/48718

[codecov[bot]]

Codecov Report

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

Project coverage is 86.70%. Comparing base (9fe827d) to head (84f3fc6).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #523 +/- ## ========================================== - Coverage 89.65% 86.70% -2.96% ========================================== Files 24 24 Lines 1760 1760 ========================================== - Hits 1578 1526 -52 - Misses 182 234 +52 ```

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[randomir]

Looks like tests.test_virtual_graph_composite.TestVirtualGraphWithMockDWaveSampler.test_smoke now segfaults on python 3.8-3.10 running on M1.

The minimal segfault code is:

from dwave.system.composites import VirtualGraphComposite
from dwave.system.testing import MockDWaveSampler

child_sampler = MockDWaveSampler()
sampler = VirtualGraphComposite(child_sampler, {'a': [0]}, flux_bias_num_reads=1)

[arcondello]

Seems to be an issue with SciPy. I tested a few versions and while scipy~=1.8.0 fails, scipy==1.9.0 succeeds.

[randomir]

@thisac, good catch. I've updated macos jobs (for consistency if for nothing else), although it doesn't seem to make that much of a difference here (maybe it's the new mac? or new OS? homebrew update used to be excruciatingly slow on circleci, but maybe they are caching it on their infra now :shrug:).