avoid pulling in Rust on FreeBSD

[duckinator]

this is apparently due to depending on pydantic

[duckinator]

i might try msgspec https://github.com/jcrist/msgspec

it still relies on C, but it feels like it's less obtuse than pydantic while doing more config validation.

problem is, as long as we have a compiled dependency, zipapps aren't really an option afaik.

[AstraLuma]

Also comes up in alpine builds and weird platforms.