Run typos with a GitHub action on PRs

[fturmel]

False positives are infrequent enough that I think we could give this a shot. Let me know what you think.

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

[netlify]

✅ Deploy Preview for codingtrain ready!

Name	Link
🔨 Latest commit	a8f05b0
🔍 Latest deploy log	https://app.netlify.com/sites/codingtrain/deploys/6738fa211e8ea90008eb8ef0
😎 Deploy Preview	https://deploy-preview-1770--codingtrain.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[shiffman]

This is great, totally worth doing! The main thing that comes up with something like this is that the YT descriptions won't be fixed and I still have to manually do them. But that's mostly on me b/c @dipamsen did excellent work in #1621 and I really need to figure out a process for running it.

[fturmel]

The hope is that with typos running against PRs automatically, we'll be able to catch these mistakes before the YouTube description gets set in the first place.