Divide by zero in `_beta_pdf`

[ntoxeg]

[/usr/local/lib/python3.10/dist-packages/scipy/stats/_continuous_distns.py:608](): RuntimeWarning: divide by zero encountered in _beta_pdf
  return _boost._beta_pdf(x, a, b)

Happens while running the Cartpole notebook, during the learning phase.

[ntoxeg]

This also happens when running the Chase example.

@ngeiswei

[ngeiswei]

I know, it's coming from the differential entropy filter. I've decided to disable it by default for now, no one (including myself) is using it at the moment anyway.