cuml.accel SVM onnx support

[jcrist]

• Adds support for skl2onnx to work with SVC/SVR under cuml.accel
• Updates tests to fix xfails
• Removes onnx notes in the cuml.accel limitations
• Also removes the notes on segfaults for SVC/SVR in that section. The cause there doesn't make sense (our test suite intermingles these estimators all the time and never sees these issues), and I cannot reproduce the issue locally.

Fixes #7822

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📥 Commits

Reviewing files that changed from the base of the PR and between 0b19540 and 2b62bdd.

📒 Files selected for processing (4)

• docs/source/cuml-accel/limitations.rst
• python/cuml/cuml/accel/_overrides/sklearn/svm.py
• python/cuml/cuml_accel_tests/test_onnx.py
• python/cuml/cuml_accel_tests/upstream/scikit-learn/xfail-list.yaml

💤 Files with no reviewable changes (2)

• python/cuml/cuml_accel_tests/upstream/scikit-learn/xfail-list.yaml
• docs/source/cuml-accel/limitations.rst

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📝 Walkthrough

Summary by CodeRabbit

• Bug Fixes

  • Improved support for SVC and SVR by aligning their exposed attributes with expected behavior.
  • Suppressed an unnecessary warning during linear SVC/SVR ONNX conversion and execution.

• Documentation

  • Updated the accelerator limitations page to reflect the current SVR fallback conditions.

• Tests

  • Adjusted test coverage to match the latest SVC/SVR behavior and removed an outdated expected-failure case.

Walkthrough

This PR updates proxy attribute metadata for SVC/SVR under cuml.accel (replacing _not_implemented_attributes with _other_attributes containing _gamma), removes the xfail_proxy_private_attr ONNX test marker in favor of filterwarnings, updates a scikit-learn xfail list entry, and trims stale SVR documentation notes.

Changes

SVC/SVR proxy attribute and ONNX xfail fix

Layer / File(s)	Summary
SVC/SVR proxy attribute metadata python/cuml/cuml/accel/_overrides/sklearn/svm.py	_not_implemented_attributes is replaced with _other_attributes = frozenset(("_gamma",)) for both SVC and SVR.
ONNX conversion test updates python/cuml/cuml_accel_tests/test_onnx.py	Removes the xfail_proxy_private_attr marker and replaces its use in SVC/SVR linear-kernel parametrizations with pytest.mark.filterwarnings ignoring a FutureWarning about deprecated `prob[A
Upstream scikit-learn xfail list update python/cuml/cuml_accel_tests/upstream/scikit-learn/xfail-list.yaml	Replaces test_gamma_scale with test_svc_raises_error_internal_representation in the cuml_accel_invalid_sklearn_tests tests list.
Documentation cleanup for SVR limitations docs/source/cuml-accel/limitations.rst	Removes the SVR "Additional notes" section (ONNX export note and SVR/LinearSVR segfault note), retaining only CPU-fallback conditions.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• rapidsai/cuml#7805: Both PRs modify test_onnx.py around SVC/SVR xfail/marker handling for private attributes during ONNX conversion.
• rapidsai/cuml#7929: Both PRs modify the SVR section of docs/source/cuml-accel/limitations.rst.
• rapidsai/cuml#8223: Both PRs touch SVC/SVR proxy attribute metadata and ONNX test warning handling for deprecated prob[A|B] attributes.

Suggested labels: Cython / Python

Suggested reviewers: viclafargue, csadorf

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title matches the main change: enabling SVC/SVR ONNX support under cuml.accel.
Description check	✅ Passed	The description is directly related to the PR and summarizes the test and documentation updates.
Linked Issues check	✅ Passed	The PR addresses #7822 by removing the ONNX xfail path, updating docs, and fixing the proxy attribute needed for SVC/SVR.
Out of Scope Changes check	✅ Passed	The changes stay within the issue scope and only adjust ONNX support, tests, and related documentation.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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[jcrist]

/merge