[MAINT][WIP] Add pytest-mpl unit tests to check ouput changes in plots

[ymzayek]

• Closes None

This was referenced in an issue or PR but I cannot find where...

This is a suggestion to add specific tests to make sure plotting function outputs don't change accidentally.

We might not want this so this is just a very basic WIP so we can discuss it

[github-actions]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (c8aed35) 92.00% compared to head (d19cae4) 91.92%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4123      +/-   ##
==========================================
- Coverage   92.00%   91.92%   -0.08%     
==========================================
  Files         145      145              
  Lines       16378    16378              
  Branches     3431     3431              
==========================================
- Hits        15069    15056      -13     
- Misses        768      779      +11     
- Partials      541      543       +2     

Flag	Coverage Δ
macos-latest_3.10_test_plotting	91.78% <ø> (ø)
macos-latest_3.11_test_plotting	91.78% <ø> (ø)
macos-latest_3.12_test_plotting	91.78% <ø> (ø)
macos-latest_3.8_test_plotting	91.74% <ø> (ø)
macos-latest_3.9_test_plotting	91.75% <ø> (ø)
ubuntu-latest_3.10_test_plotting	91.78% <ø> (ø)
ubuntu-latest_3.11_test_plotting	91.78% <ø> (ø)
ubuntu-latest_3.12_test_plotting	91.78% <ø> (ø)
ubuntu-latest_3.12_test_pre	91.78% <ø> (ø)
ubuntu-latest_3.8_test_min	68.97% <ø> (ø)
ubuntu-latest_3.8_test_plot_min	?
ubuntu-latest_3.8_test_plotting	91.74% <ø> (ø)
ubuntu-latest_3.9_test_plotting	91.75% <ø> (ø)
windows-latest_3.10_test_plotting	91.76% <ø> (ø)
windows-latest_3.11_test_plotting	91.76% <ø> (ø)
windows-latest_3.12_test_plotting	91.76% <ø> (ø)
windows-latest_3.8_test_plotting	91.72% <ø> (ø)
windows-latest_3.9_test_plotting	91.73% <ø> (ø)

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