The lecture https://python.quantecon.org/bayes_nonconj.html is out of date and contains typos.

Due to advances in JAX we should be able to drop pytorch/pyro and just use numpyro.

Other fixes:

• all code to PEP8
• link to QuantEcon lecture needs to be fixed @mmcky (improved documentation in b927abd)
• the lecture mentions pymc4 but does not use it
• jax is imported but do we use it directly?

Some text will need to be adjusted, e.g.,

"In particular, we implement Stochastic Variational Inference (SVI) machinery in both Pyro and Numpyro."

I'm not sure if these are also worth considering:

• https://blackjax-devs.github.io/blackjax/
• https://github.com/jax-ml/oryx

@kp992 should be able to judge best where the ecosystem is going.