array-api-tests 2026.02.26: target the Array API 2025.12 revision

Merge pull request #373 from ev-br/skip_xfails

ENH: add ARRAY_API_TESTS_XFAIL_MARK to turn xfails into skips

Improved values testing for elementwise and operators tests.

array-api-tests version 2022.1 (first version)