Fix CI

[kenneth-meyer]

Now that the repo is public, we can fix our CI pipeline! As a refresher, here are some good ideas for handling this:

• check important tests before each merge to main
• separate unit tests from benchmarks to make the above-mentioned tests lean
• use pytest / unittest to modularize testing, run simple tests on multiple element types, and more
• use a CPU for tests that occur on every merge / PR, and have a GPU-based test suite for tests that are run less frequently (and likely run locally, to avoid eating up our GPU allocation on github CI servers)

@BenThomas324 I can get started on this with an example of how to parameterize a test across each supported element type, will keep you posted!