When you install pymc-marketing numpyro is not a requirement, but in several examples it's used.

I suggest having a pymc_marketing._numpyro_if_available variable (name up to discussion) that is "numpyro" if it's installed and "pymc" if not. Then the examples where we may want numpyro would have nuts_sample=_numpyro_if_available, and work.

In #1357 I actually changed one of the NBs to have a try/except but that clutters NBs a bit too much?