[BUG] Deprecation warnings with Altair v5 #274

Describe the bug
Deprecation warnings with Altair version 5, like

python3.11/site-packages/altair/utils/deprecation.py:65: AltairDeprecationWarning: 'selection_single' is deprecated.  Use 'selection_point'
  warnings.warn(message, AltairDeprecationWarning, stacklevel=1)

To Reproduce
Steps to reproduce the behavior:
Open and execute the notebook docs/source/examples/plotting_example.ipynb.

Expected behavior
No warnings.