use v4 artifact

[timmysilv]

Context for changes and related issues

The v3 (and under) artifact actions are deprecated, and must be updated by end of January.

Improvements

• Bump the upload-artifact and download-artifact versions to v4

Benefits, drawbacks, and extensions

• Our wheel upload actions won't suddenly break in February

Checklist and integration statements

• My Python and C++ codes follow this project's coding and commenting styles as indicated by existing files. Precisely, the changes conform to given black and pylint configurations.
• I have performed a self-review of these changes, checked my code (including for codefactor compliance), and corrected misspellings to the best of my capacity. I have synced this branch with others as required.
• I have added context for corresponding changes in documentation and README.md as needed.
• I have added new workflow CI tests for corresponding changes, ensuring codecoverage is 95% or better, and these pass locally for me.
• I have updated CHANGELOG.md following the template. I recognize that the developers may revisit CHANGELOG.md and the versioning, and create a Special Release including my changes.