Update warning checker configuration to include UserWarning
@mmcky : one for the warning checker: /home/runner/miniconda3/envs/quantecon/lib/python3.12/site-packages/IPython/core/pylabtools.py:170: UserWarning: Creating legend with loc="best" can be slow with large amounts of data. fig.canvas.print_figure(bytes_io, **kw)
Originally posted by @jstac in QuantEcon/lecture-python.myst#545 (comment)