Errors in GP-circular notebook

Notebook Title: GP-Circular
Notebook URL: URL

Issue description

The notebook is broken, possibly due to new version of PyMC.
I advise to follow the link for the source code. Running the last command

 plot_kernel_results(circular)

gives error on command

trace = pm.sample_posterior_predictive([mp], var_names=["y"], samples=100)

saying that keyword 'samples' is unknown.

This keyword is also absent in official docs right now,
but is present in previous tutorials, say in year 2022 (it is actually a pain that it was changed and
who the hell knows how to set number of samples).

I have tried to just remove this keyword (assuming that some default number of samples will be
generated) - but then next command fails

    paths = plt.polar(angles, trace["y"].T, color="b", alpha=0.05)

with error that 'trace' has no key 'y'.

Start with examples/gaussian_processes/GP-Circular.ipynb and run plot_kernel_results(circular) to reproduce the failure. Inspect the pm.sample_posterior_predictive call and the subsequent trace["y"] access; done means the notebook runs through the polar plot without the reported keyword or missing-key errors.