Add mypy or pyright checker on deploy

[virtuald]

Could help out teams not deploy bad code.

Mypy tends to have a lot of false positives, would need to ensure that any solution was either optional or not obnoxious when enabled.

[auscompgeek]

mypy took upwards of half a minute to run on my team's codebase last season in GitHub Actions. pyright was a lot faster, but also a fair bit more strict than mypy by default.