feat: expose voronoi to python

[BeaMarton13]

I used Cody for the functions.

• [x] By submitting this pull request, I assign the copyright of my contribution to The igraph development team.

[ntamas]

Try to avoid re-formatting the .py files even if your IDE insists on reformatting. It makes it much harder to go through the PR and separate pure formatting-only modifications from the "real" part of the PR.

[szhorvat]

I think modularity should not be a parameter. Instead, let modularity be computed unconditionally. This takes little time compared to the rest of the algorithm.

[szhorvat]

There are some warnings when building docs. Can you help me by investigating the cause?

WARNING: /Users/szhorvat/Repos/python-igraph/.venv/lib/python3.13/site-packages/igraph/_igraph.abi3.so:???: Cannot parse signature of igraph._igraph.GraphBase.community_voronoi
WARNING: /Users/szhorvat/Repos/python-igraph/.venv/lib/python3.13/site-packages/igraph/community.py:333: Cannot find link target for "igraph.Graph.ecc"
WARNING: /Users/szhorvat/Repos/python-igraph/.venv/lib/python3.13/site-packages/igraph/_igraph.abi3.so:???: Documented parameter "lengths" does not exist
WARNING: /Users/szhorvat/Repos/python-igraph/.venv/lib/python3.13/site-packages/igraph/_igraph.abi3.so:???: Documented parameter "weights" does not exist
WARNING: /Users/szhorvat/Repos/python-igraph/.venv/lib/python3.13/site-packages/igraph/_igraph.abi3.so:???: Documented parameter "mode" does not exist
WARNING: /Users/szhorvat/Repos/python-igraph/.venv/lib/python3.13/site-packages/igraph/_igraph.abi3.so:???: Documented parameter "radius" does not exist
WARNING: /Users/szhorvat/Repos/python-igraph/.venv/lib/python3.13/site-packages/igraph/__init__.py:3993: Cannot find link target for "igraph.Graph.ecc"

@BeaMarton13, I just fixed this, please see the last commit (7c30c6ccd58af9c6bd64062e0dbe28c9cc820852). It's something very easy to miss.

[szhorvat]

@ntamas I believe this is ready. Please have a look and merge. Please use only squash-and-merge as the commit history is a mess!

[ntamas]

Thanks!