Latexified and blackjaxified figure 17.18 `gp_kernel_opt.ipynb` (#919)
Latexified and blackjaxified figure 17.18 `gp_kernel_opt.ipynb` (#919)

* latexify `gp_kernel_opt` notebook. add blackjax

* refactoring
probml/pyprobml,probml/pyprobml,probml/pyprobml,probml/pyprobml