Resolve circular import of the internal submodule

[dodamih]

Our codebase has a circular import where zetta_utils.load_all_modules() loads internal, which loads from zetta_utils. This seems to be the cause of issues with using dill.dumps with recurse=True.

I have investigated using cloudpickle as an alternative, but this seems result in probabilistically inconsistent serialisation across processes that have been started using spawn. It seems to happen very consistently on GitHub CI but not when running locally, and investigating the serialised bytecode shows that the entrypoints are different:

  370: \x8c         SHORT_BINUNICODE '/home/runner/work/zetta_utils/zetta_utils/tests/unit/mazepa/test_id_generation.py'

vs.

  328: \x8c         SHORT_BINUNICODE 'unit.mazepa.test_id_generation'

It's not definite, but the most likely culprit for this is still the circular import as partially initialised modules are known to cause inconsistent behaviour across runs.