Use v4 upload artifact for unit test github workflow.

[cody-littley]

Why are these changes needed?

Fixes a failure caused by the deprecation of the old upload artifact workflow.

Checks

• [x] I've made sure the lint is passing in this PR.
• [x] I've made sure the tests are passing. Note that there might be a few flaky tests, in that case, please comment that they are not relevant.
• [ ] I've checked the new test coverage and the coverage percentage didn't drop.
• Testing Strategy
  • [x] Unit tests
  • [ ] Integration tests
  • [ ] This PR is not tested :(