Regression in pyplot / samples

Problem description

An upstream update presumably broke the samples GH test runners (see #1531 or #1262)

Steps to reproduce

Use GH Action to test samples
See error '....'

[...]
Traceback (most recent call last):
  File "samples/python/kinetics/mechanism_reduction.py", line 95, in <module>
    plt.tight_layout()
  File "/opt/hostedtoolcache/Python/3.8.17/x64/lib/python3.8/site-packages/matplotlib/pyplot.py", line 2349, in tight_layout
    return gcf().tight_layout(pad=pad, h_pad=h_pad, w_pad=w_pad, rect=rect)
  File "/opt/hostedtoolcache/Python/3.8.17/x64/lib/python3.8/site-packages/matplotlib/figure.py", line 3547, in tight_layout
    _api.warn_external('The figure layout has changed to tight')
  File "/opt/hostedtoolcache/Python/3.8.17/x64/lib/python3.8/site-packages/matplotlib/_api/__init__.py", line 390, in warn_external
    warnings.warn(message, category, stacklevel)
UserWarning: The figure layout has changed to tight
Error: Process completed with exit code 1.

Behavior

The UserWarning crashes the GH Action.

System information

Cantera version: 3.0.0b1
OS: GH Runner / Ubuntu 20.04 and 22.04

Cantera / cantera

Regression in pyplot / samples #1532