Fix a Khiops type guessing error when reading a numpy string dtype

[tramora]

• All the numpy string dtypes ('str' and 'string') must be considered

Fixes #607

---

TODO Before Asking for a Review

• Rebase your branch to the latest version of main (or main-v10)
• Make sure all CI workflows are green
• When adding a public feature/fix: Update the Unreleased section of CHANGELOG.md (no date)
• Self-Review: Review "Files Changed" tab and fix any problems you find
• API Docs (only if there are changes in docstrings, markdown files or samples):
  • Check the docs build without warning: see the log of the API Docs workflow
  • Check that your changes render well in HTML: download the API Docs artifact and open index.html
  • If there are any problems it is faster to iterate by building locally the API Docs

[popescu-v]

Move the test to test_dataset_class.py, because no error / failure-mode is checked here; just normal behavior.

[tramora]

Fixed

[popescu-v]

For a minimally-invasive change, I'd do just:

elif lower_numpy_type in ["str", "string"]

Otherwise, the scope would be larger than the support Khiops is committed to (just Pandas, with its NumPy dependency, plus SciPy - for the sparse data):

isinstance(pd.StringDtype(storage="pyarrow"), pd.StringDtype) # => True
str(pd.StringDtype(storage="pyarrow")).lower() in ("string", "str") # => False, because "string[pyarrow]" not in ["string", "str"]

Adding further support (PyArrow, BigQuery) seems out of the scope of the current PR and deserves further assessment IMHO.

[tramora]

You are right. I changed the test

[popescu-v]

See the comments.