ast class deprecations

[greyltc]

A few ast module classes being used here were depreciated in python 3.8 and removed from 3.14:

https://github.com/python/cpython/blob/48795b6460e16dff72add0675a7bf8e1f029108e/Doc/library/ast.rst?plain=1#L144-L148

For example, this line fails today on the latest stable python release:

cadquery/cadquery/cqgi.py

Line 494 in fe53ca0

if type(value_node) == ast.Num:

because ast.Num is gone.

[greyltc]

fc85e1d might fix this, but I'm still getting odd test suite failures like

E       AssertionError: 'this is a string' != '33.33'