REL: ship array API test xfails in wheels

[nightcityblade]

Closes #239.

Summary

Include array-api-tests-xfails.txt in built wheels so downstream test suites can retrieve the matching expectations through importlib.metadata.files("array_api_strict").

Validation

• Full test suite: 770 passed
• ruff check .: passed
• validate-pyproject pyproject.toml: passed
• Built both wheel and sdist and ran twine check --strict: passed
• Installed the built wheel into a clean environment and verified its shipped xfail file byte-for-byte against the source file

AI generation disclosure

OpenAI Codex was used to implement the packaging configuration and run the validation steps. The configuration change was AI-assisted and verified against the contents of a locally built and installed wheel.

[nightcityblade]

CI follow-up: the only failure is the randomized Array API conformance test array_api_tests/test_linalg.py::test_trace in the Ubuntu / Python 3.10 / NumPy 1.26 job while testing API version 2025.12. Hypothesis generated a uint32 case where the test reported Array(5) != Array(1).

This PR changes only setuptools package-data metadata in pyproject.toml; it does not modify trace or any runtime implementation. The same job passed its 2023.12 and 2024.12 runs, the equivalent Python 3.10 / NumPy 1.26 jobs passed on macOS and Windows, every other matrix job passed, and this exact Ubuntu matrix has passed on recent upstream runs.

I attempted to rerun the failed job, but GitHub requires repository admin permission. Could a maintainer please rerun it? I don't believe a code change in this PR would be appropriate for this unrelated property-test failure.

[betatim]

Please also package the other xfail files.

[nightcityblade]

Done — the wheel and sdist now include array-api-tests-macos-xfails.txt and array-api-tests-windows-xfails.txt alongside the shared xfail file. I rebuilt both distributions, verified all three files are present in each artifact, ran twine check --strict, and ran Ruff; all passed.

[betatim]

Please move the xfail files inside array_api_strict/ instead of using ../ in package-data. As written they install to the top level of site-packages. After this you will also have to update the CI workflow, docs link, and array-api-tests workflow accordingly (we use the files there so we need to coordinate if we move the files). array-api-tests' .github/workflows/test.yml:37 hardcodes /tmp/array-api-strict/array-api-tests-xfails.txt. Either coordinate a change there or keep the root path working during a transition phase.

It would also be good to add a test that checks that using importlib.resources.files("array_api_strict") / "array-api-tests-xfails.txt" to load the file works.

What do you think @ev-br ?