`wrap_viscm` snippet in docs raises error

[mfisher87]

This occurs even with the plots extra installed (pip install cmocean[plots])

Traceback (most recent call last):
  File "/home/robatt/Projects/_tmp/viscm/test.py", line 3, in <module>
    cmocean.plots.wrap_viscm(cmocean.cm.haline)
    ^^^^^^^^^^^^^
AttributeError: module 'cmocean' has no attribute 'plots'

[mfisher87]

This gets closer...

import cmocean
from cmocean.plots import wrap_viscm

wrap_viscm(cmocean.cm.haline, saveplot=False)

But now I get this error with pyside6 or pyqt6:

  File "/home/robatt/Projects/_tmp/viscm/test.py", line 4, in <module>
    wrap_viscm(cmocean.cm.haline, saveplot=False)
  File "/home/robatt/Projects/_tmp/viscm/.venv/lib/python3.11/site-packages/cmocean/plots.py", line 127, in wrap_viscm
    from viscm import viscm
  File "/home/robatt/Projects/_tmp/viscm/.venv/lib/python3.11/site-packages/viscm/__init__.py", line 5, in <module>
    from .gui import viscm, viscm_editor
  File "/home/robatt/Projects/_tmp/viscm/.venv/lib/python3.11/site-packages/viscm/gui.py", line 18, in <module>
    from matplotlib.backends.qt_compat import QtWidgets, QtCore, QtGui, _getSaveFileName
ImportError: cannot import name '_getSaveFileName' from 'matplotlib.backends.qt_compat' (/home/robatt/Projects/_tmp/viscm/.venv/lib/python3.11/site-packages/matplotlib/backends/qt_compat.py)