matplotlib is required even when dymos is installed with no extras

[swryan]

Description

When installing dymos without any extras (e.g. 'test', 'notebooks' or 'docs'), matplotlib is not installed.

However it is not possible to import dymos without matplotlib

Example

~$ conda create -n dymos-1.10.0 numpy scipy cython swig

[.. deleted ..]

~$  conda activate dymos-1.10.0

~$ pip install dymos
Collecting dymos
  Using cached dymos-1.10.0-py3-none-any.whl

[.. deleted ..]

~$ python -c "import dymos"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/home/swryan/miniconda3/envs/dymos-1.10.0/lib/python3.12/site-packages/dymos/__init__.py", line 8, in <module>
    from .run_problem import run_problem
  File "/home/swryan/miniconda3/envs/dymos-1.10.0/lib/python3.12/site-packages/dymos/run_problem.py", line 8, in <module>
    from dymos.visualization.timeseries_plots import timeseries_plots
  File "/home/swryan/miniconda3/envs/dymos-1.10.0/lib/python3.12/site-packages/dymos/visualization/timeseries_plots.py", line 7, in <module>
    import matplotlib
ModuleNotFoundError: No module named 'matplotlib'

Dymos Version

1.10.0

Relevant environment information

No response