FIX Add support for scikit-learn 1.8

[dherrera1911]

PR description at a high level:

Support scikit-learn 1.8, that introduced a breaking change. Maintain compatibility with versions <=1.7.

Fixes #359

Describe changes:

In scikit-learn 1.8, the parameter force_all_finite in the functions check_array() and check_X_y() was deprecated, and replaced for ensure_all_finite.

The function _utils.py::check_input() uses the parameter force_all_finite, making the package fail as described in #359.

In this PR, we introduce the local wrapper functions _check_array() and _check_X_y() inside of _utils.py. These wrappers work like their scikit-learn counterparts, but are able to take both force_all_finite and ensure_all_finite as inputs. Now _utils.py calls the wrappers instead of directly calling the functions.

Outstanding questions:

For transparency I mention that the original version of this PR was generated by a coding agent. After reviewing it, I concluded that the approach is sound. I did modify it considerably to make it simpler.

I have not tested this solution thoroughly, but I can run the relevant parts of the testing suite.

[dherrera1911]

I ran the tests in test/test_utils.py, and everything seems to be working good. Actually, the current version of metric-learn was throwing errors in these tests even before it broke, because of scikit-learn deprecation warnings.

For reference, this branch passes all tests with scikit-learn 1.8, while main fails a lot of tests.

Interestingly, when using scikit-learn 1.7, both this branch and main throw a bunch of errors saying e.g. FAILED test/test_utils.py::test_check_tuples_valid_tuple_size[2] - assert 4 == 0. This is because in both cases, the pattern below

  with warnings.catch_warnings(record=True) as record:
    check_input(tuples, type_of_inputs='tuples', preprocessor=None)
  assert len(record) == 0

I looked into one of these tests, and as I supposed, it was a FutureWarning from scikit-learn, warning about ensure_all_finite:

is catching `scikit-learn` warnings:

sklearn/utils/deprecation.py:132: FutureWarning: 'force_all_finite' was renamed to 'ensure_all_finite' in 1.6 and will be removed in 1.8.
warnings.warn(

In sum, it the current PR makes `metric-learn` work with `scikit-learn` 1.8, at least in the tests I ran and the use cases I tested for my own work.

[perimosocordiae]

Thanks! I had to manually enable the CI to run on this PR, but it started now.

[perimosocordiae]

I'm confused why this line is showing up as part of the diff. Maybe a line-ending related change?