Custom PPL support should be external to `tinygp`?

[femtomc]

Hi - perusing this library, I noticed that numpyro has special built-in support - and is a dependency.

My short, brute question is: why keep this here?

This seems like it should live somewhere entirely different - like in a numpyro/tinygp compat layer (within numpyro) - but not within this repo, if the goal is to keep it PPL compat agnostic.

Another viewpoint: if I'm developing a PPL, and wish to use tinygp - I likely don't want my dependency chain to also depend on numpyro (following the "lightweight" philosophy of tinygp) which I don't need.

[femtomc]

Edit: Realize this is specified via tinygp[numpyro] or the like -- so numpyro is not an active dependency. Which is nice! That was my main concern.