Simplify Package Download in pkgci_shark_ai.yml

[renxida]

Comments from Scott on #780

I'd like to simplify these steps as we add more pkgci_*.yml workflows, but this is fine for now.

For the downloads, actions/download-artifact supports downloading multiple artifacts using some pattern: https://github.com/actions/download-artifact?tab=readme-ov-file#download-multiple-filtered-artifacts-to-the-same-directory . Could try with

pattern: snapshot-*-cp${{ env.PY_VERSION_NO_DOT }}-*

Note that sharktank and shark-ai aren't dependent on Python versions, and audit_wheel actually removes the cp311 from the names:

So if we keep the versions in the names, we can have a single download step that filters. If we remove the versions, we could either download all artifacts (no filtering at all) or two download steps, one that filters for cp311 and one that filters for py3-none.

For the PY_VERSION_NO_DOT, I don't see a way to get actions/setup-python to use the cp311 syntax: https://github.com/actions/setup-python/blob/main/docs/advanced-usage.md.

The downloads are fast (less than 10MB total, taking seconds or less), so I'd probably just download all artifacts then make sure setup_venv.py respects the selected Python version and only tries to install compatible packages from the download.