Fixed matplotlib calls that were broken by a change in the matplotlib API

[swryan]

Summary

• Updated calls to matplotlib's cm.get_cmap() function to use the colormap registry
• Updated baseline versions of dependencies used in continuous integration testing
• Added a preinstall of matplotlib 3.5 as the oldest supported version in the Tests workflow
• Added a pipdeptree step to the Tests workflow to assist in determining the cause of dependency changes
• Added a Numpy 2.0 compatibility check to the Tests workflow

Related Issues

• Resolves #1068

Backwards incompatibilities

None

New Dependencies

None

[review-notebook-app[bot]]

Check out this pull request on 

See visual diffs & provide feedback on Jupyter Notebooks.

---

Powered by ReviewNB

[coveralls]

coverage: 92.341% (-0.2%) from 92.549% when pulling 028e08218059fb57929fec4983fca5aeb8e5c207 on swryan:1068_mpl into d6813fe53eb5f6765dfe20749ab71ea6cfa4dac8 on OpenMDAO:master.