Updating pseudopy to the recent python ecosystem evolutions

[nennigb]

This PR aims at updating pseudopy to the recent python ecosystem evolutions.

This PR contains five kinds of modification:

1. Shapely v2.0 evolution :

   • cascaded_union has been removed in v2.0.0. https://shapely.readthedocs.io/en/stable/migration.html indicates to use shapely.ops.unary_union instead.
   • Iteration over multi-part geometries raise an error. https://shapely.readthedocs.io/en/stable/migration.html indicates to use .geoms attribute instead.

2. Matplotlib evolution on contour since v3.8
   see https://discourse.matplotlib.org/t/collections-attribute-deprecation-in-version-3-8/24164/7

3. Numpy v2 evolution

   • Change np.Inf into np.inf when required
   • Change np.complex to complex

4. Python packaging evolution (distutils has been removed)

   • Add explicitly nose2 dependancy
   • Remove setup.py and use pyproject.toml to stay closer to new standards
   • Use hatchling as build-backend. Hatchling is developed and maintained by the PyPA (Python Packaging Authority)
   • remove outdated requirements.txt and MANIFEST.in

5. Update tests

   • fix dependencies evolutions
   • move to nose2
   • add github action CI script

6. Fix missing argument to use lanczos

   • Uniformize 'lanczosinv' (undefined) to 'lanczos'
   • Add missing 'method' argument in super call

All tests pass and the CI output can be checked on
https://github.com/nennigb/pseudopy/actions/runs/28940523964
for python 3.11 to 3.14

Let me know if you want that I split the PR or I make some modification.