Change import of is_prng_key

[adrn]

I'm getting a DeprecationWarning from using numpyro.distributions.util.is_prng_key():

Example:

python -W "default::DeprecationWarning" -c "from numpyro.distributions.util import is_prng_key; is_prng_key(42)"

It looks like it was moved in this PR:
pyro-ppl/numpyro#1642

This would require numpyro>=0.13.1 https://github.com/pyro-ppl/numpyro/releases/tag/0.13.1 -- do you want me to add some backwards compatibility here? Or add the numpyro version constraint?

[dfm]

Thanks! Let's update the numpyro version constraint. I don't think we need to maintain too much backwards compatibility!

[adrn]

Hm, I'm guessing the 3.8 build is failing because the recent numpyro depends on a newer version of jax that requires python >= 3.9 (https://pypi.org/project/jax/0.4.14/) -- I'll update the min python version but let me know if you prefer a different solution!

[dfm]

Please do!

[adrn]

Done in the last commit!

[dfm]

Thanks!!