Fix warnings in code: webgl 32bit, json compliance (and maybe the scipy sin/cos one).

[moorepants]

WARNING: Cell printed to stderr:
/tmp/ipykernel_3283/3139199006.py:1: DeprecationWarning: scipy.cos is deprecated and will be removed in SciPy 2.0.0, use numpy.cos instead
  sp.cos(12.0)

WARNING: Cell printed to stderr:
/home/runner/micromamba-root/envs/multibody-book/lib/python3.9/site-packages/jupyter_client/session.py:718: UserWarning: Message serialization failed with:
Out of range float values are not JSON compliant
Supporting this message is deprecated in jupyter-client 7, please make sure your message is JSON-compliant
  content = self.pack(content)

WARNING: Cell printed to stderr:
/home/runner/micromamba-root/envs/multibody-book/lib/python3.9/site-packages/pythreejs/traits.py:203: UserWarning: 64-bit data types not supported for WebGL data, casting to 32-bit.
  warnings.warn('64-bit data types not supported for WebGL '