CI: run tests against the 2025.12 revision

[ev-br]

No description provided.

[Copilot]

Pull request overview

This PR updates the Array API test suite version from 2024.12 to 2025.12 in the GitHub Actions CI workflow. The change affects only the testing infrastructure, not the actual implementation code.

Changes:

• Update ARRAY_API_TESTS_VERSION environment variable from 2024.12 to 2025.12 in the CI workflow

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[Copilot]

The CI test version is being updated to 2025.12, but the actual implementation still declares support for 2024.12 in multiple places. There is a discrepancy between what's being tested and what the code declares it supports. The following files should be reviewed and potentially updated to maintain consistency:

1. array_api_compat/common/_helpers.py (line 59) - _API_VERSIONS still only includes "2024.12"
2. array_api_compat/numpy/__init__.py (line 29) - __array_api_version__ is "2024.12"
3. array_api_compat/cupy/__init__.py (line 15) - __array_api_version__ is "2024.12"
4. array_api_compat/dask/array/__init__.py (line 12) - __array_api_version__ is "2024.12"
5. array_api_compat/torch/__init__.py (line 16) - __array_api_version__ is "2024.12"
6. docs/index.md (lines 15-16) - Documentation still references 2024.12

If the intent is to test against 2025.12 while still implementing 2024.12, this should be documented. Otherwise, these files should be updated together to ensure the library declares support for the version it's being tested against.

[ev-br]

CI failures are list/tuples in meshgrid et al. Merge as is, and sort out the failures in gh-380.