Fix pip check for py-xgboost

[hcho3]

Closes #190

Related: dmlc/xgboost#10755

• Run pip check as part of test step
• Remove nvidia-nccl-cu12 dependency from pyproject.toml
• Use the correct platform tag using pip

Checklist

• Used a personal fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)

[hcho3]

@conda-forge-admin, please rerender

[conda-forge-webservices]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe/meta.yaml) and found it was in an excellent condition.

[jakirkham]

Thanks Hyunsu! 🙏

Added a suggestion below for test requirements

[jakirkham]

Thanks Hyunsu! 🙏

Had minor suggestions to tidy the patches. The same strategy may be useful upstream to simplify PR review

[jakirkham]

Thanks Hyunsu! 🙏

Both this and the upstream PR LGTM

Please feel free to merge when ready 🙂

[jakirkham]

Some of the builds here had failed on main even though they passed in the PR. Think this was due to unrelated changes in other packages (linkage checks that failed in the builds here). Have restarted and these appear to have cleared out