[Bug] MatplotlibDeprecationWarning: The set_window_title function was deprecated in Matplotlib 3.4 and will be removed two minor releases later

[sanjayankur31]

Is your feature request related to a problem? Please describe.
Matplotlib will deprecate the set_window_title function in the coming releases

Describe the solution you'd like
We should update the pynml code to note use it now.

Describe alternatives you've considered
NA

Additional context
Full deprecation warning:

/usr/lib/python3.9/site-packages/pyneuroml/pynml.py:1688: MatplotlibDeprecationWarning: 
The set_window_title function was deprecated in Matplotlib 3.4 and will be removed two minor releases later. Use manager.set_window_title or GUI-specific methods instead.
  fig.canvas.set_window_title(title)