Convert tests to AVA

Currently tests need to be run manually and verified visually. Plus they don't take in any token so you'll quickly run into the API limits.

- [ ] Automate tests with AVA
- [ ] Use `process.env.GITHUB_TOKEN`
- [ ] Optionally configure GitHub Actions so that GITHUB_TOKEN is automatically present for the current repo

Start by locating the repository's current manually run tests and package configuration; no specific files or test entry points are named in the issue. The work is done when AVA automates the checks, requests use process.env.GITHUB_TOKEN, and the optional GitHub Actions setup is either configured or explicitly scoped out.

Written by the indexing model from the issue text.