Add `typos` CI lint

[DecDuck]

Add typos to GitHub Actions to catch typos before we merge.

https://github.com/crate-ci/typos/tree/master

[DecDuck]

Nevermind, it flags a tonne in our codebase that aren't typos. Maybe someone can figure out how to only scan Markdown files or something, but at that point, it isn't worth it.