Fix build env used for testing oneMath interface

[antonwolfy]

The PR updates the file with the conda environment used to create build conda env for testing oneMath interfaces:

• forced to use DPC++ and MKL from the latest release 2025.3 (no the latest compiler packages on conda-forge yet)
• forced to install TBB from Intel channel, because MKL is not compatible with the latest tbb from the conda-forge when cmake option MKL_THREADING=tbb_thread used

Alternatively there might an approach to create the env with strict channel priority, now the default one is flexible, which can't guarantee the packages from high priority channel are installing.

• Have you provided a meaningful PR description?
• Have you added a test, reproducer or referred to an issue with a reproducer?
• Have you tested your changes locally for CPU and GPU devices?
• Have you made sure that new changes do not introduce compiler warnings?
• Have you checked performance impact of proposed changes?
• Have you added documentation for your changes, if necessary?
• Have you added your changes to the changelog?

[github-actions]

View rendered docs @ https://intelpython.github.io/dpnp/pull/2646/index.html

[github-actions]

Array API standard conformance tests for dpnp=0.20.0dev0=py313h509198e_31 ran successfully.
Passed: 1227
Failed: 0
Skipped: 9

[coveralls]

coverage: 81.51%. remained the same
when pulling bceae5d on fix-gh-action-onemath
into 5b39d66 on master.

[vlad-perevezentsev]

LGTM!
Thank you @antonwolfy for unblocking the public CI