Dev/eglaser downgrade cython

[ethanglaser]

Description

Add a comprehensive description of proposed changes

List associated issue number(s) if exist(s): #6 (for example)

Documentation PR (if needed): #1340 (for example)

Benchmarks PR (if needed): IntelPython/scikit-learn_bench#155 (for example)

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PR should start as a draft, then move to ready for review state after CI is passed and all applicable checkboxes are closed.
This approach ensures that reviewers don't spend extra time asking for regular requirements.

You can remove a checkbox as not applicable only if it doesn't relate to this PR in any way.
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Checklist to comply with before moving PR from draft:

PR completeness and readability

• I have reviewed my changes thoroughly before submitting this pull request.
• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation to reflect the changes or created a separate PR with update and provided its number in the description, if necessary.
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• I have extended testing suite if new functionality was introduced in this PR.

Performance

• I have measured performance for affected algorithms using scikit-learn_bench and provided at least summary table with measured data, if performance change is expected.
• I have provided justification why performance has changed or why changes are not expected.
• I have provided justification why quality metrics have changed or why changes are not expected.
• I have extended benchmarking suite and provided corresponding scikit-learn_bench PR if new measurable functionality was introduced in this PR.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

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see 44 files with indirect coverage changes

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[icfaust]

I am so puzzled to how the Cython version impacts that test failure

[david-cortes-intel]

@ethanglaser Are you able to isolate the test that is failing?

Perhaps this might be an actual bug on the sklearnex. This cython release included bug fixes around type inference with conflicting types, for example:
https://docs.cython.org/en/latest/src/changes.html#id4

[ethanglaser]

Is this still relevant? Looks like we have green public CI