0.4.3: Tests fail to run: ImportError: cannot import name 'bs' from 'kliff.descriptors.bispectrum'

[yurivict]

Describe the bug
Errors:

___________________________________________________________________ ERROR collecting tests/uq/test_bootstrap_empirical.py ___________________________________________________________________
ImportError while importing test module '/usr/ports/science/py-kliff/work-py311/kliff-0.4.3/tests/uq/test_bootstrap_empirical.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
/usr/local/lib/python3.11/importlib/__init__.py:126: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
tests/uq/test_bootstrap_empirical.py:9: in <module>
    from kliff.loss import Loss
kliff/loss.py:10: in <module>
    from kliff.calculators.calculator_torch import CalculatorTorch
kliff/calculators/__init__.py:9: in <module>
    from .calculator_torch import CalculatorTorch
kliff/calculators/calculator_torch.py:10: in <module>
    from kliff.dataset.dataset_torch import FingerprintsDataset, fingerprints_collate_fn
kliff/dataset/dataset_torch.py:7: in <module>
    from kliff.descriptors.descriptor import load_fingerprints
kliff/descriptors/__init__.py:1: in <module>
    from .bispectrum.bispectrum import Bispectrum
kliff/descriptors/bispectrum/bispectrum.py:4: in <module>
    from kliff.descriptors.bispectrum import bs  # C extension
E   ImportError: cannot import name 'bs' from 'kliff.descriptors.bispectrum' (/usr/ports/science/py-kliff/work-py311/kliff-0.4.3/kliff/descriptors/bispectrum/__init__.py)
______________________________________________________________________ ERROR collecting tests/uq/test_bootstrap_nn.py _______________________________________________________________________
ImportError while importing test module '/usr/ports/science/py-kliff/work-py311/kliff-0.4.3/tests/uq/test_bootstrap_nn.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
/usr/local/lib/python3.11/importlib/__init__.py:126: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
tests/uq/test_bootstrap_nn.py:12: in <module>
    from kliff.calculators import CalculatorTorch
kliff/calculators/__init__.py:9: in <module>
    from .calculator_torch import CalculatorTorch
kliff/calculators/calculator_torch.py:10: in <module>
    from kliff.dataset.dataset_torch import FingerprintsDataset, fingerprints_collate_fn
kliff/dataset/dataset_torch.py:7: in <module>
    from kliff.descriptors.descriptor import load_fingerprints
kliff/descriptors/__init__.py:1: in <module>
    from .bispectrum.bispectrum import Bispectrum
kliff/descriptors/bispectrum/bispectrum.py:4: in <module>
    from kliff.descriptors.bispectrum import bs  # C extension
E   ImportError: cannot import name 'bs' from 'kliff.descriptors.bispectrum' (/usr/ports/science/py-kliff/work-py311/kliff-0.4.3/kliff/descriptors/bispectrum/__init__.py)
______________________________________________________________ ERROR collecting tests/uq/test_bootstrap_nn_separate_species.py ______________________________________________________________

To Reproduce
pytest

Additional context
Add any other context about the problem here. For example,

• Operating system (Linux/Mac/Win) and version: FreeBSD 14.1
• Python version: 3.11