matplotlib.pyplot needs to be imported in axes.py for set_figax

[SebastienRietteMTO]

Describe the bug
Using set_figax raise an error if matplotlib.pyplot was not imported before

To Reproduce
Paro is an epygram field

Paro.scatter_with(Paro)
Traceback (most recent call last):
File "", line 1, in
File "/home/riette/EPyGrAM/src/epygram/fields/D3Field.py", line 1665, in scatter_with
fig, ax = set_figax(fig, ax, figsize=figsize)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/riette/.epygram/vortex/site/bronx/graphics/axes.py", line 22, in set_figax
plt = matplotlib.pyplot
^^^^^^^^^^^^^^^^^
File "/home/riette/virtualenvs/A/lib/python3.12/site-packages/matplotlib/_api/init.py", line 217, in getattr
raise AttributeError(
AttributeError: module 'matplotlib' has no attribute 'pyplot'

Expected behavior
No exception

Environment (please complete the following information):

• Python version: 3.12.13, matplotlib 3.9.2
• OS: linux

Additional context
Add any other context about the problem here.