pydoc-markdown requirement >= 4.6.0

[apmoore1]

pydoc-markdown has made a change since version 4.6.0 to use Novella as the render, this means the current way we create our Python API documentation needs to change if we want to use pydoc-markdown >= 4.6.0. The code that creates this Python API documentation is the ./scripts/py2md.py script.

This is not an urgent change as version 4.5.1 of pydoc-markdown works with Python versions >=3.7,<=3.10.