numpy fails because of cython

[pmiddend]

Describe the issue

I've created a super simple test repository here: https://github.com/pmiddend/poetry2nix-numpy-test

The pyproject.toml contains just numpy-1.22.4 as a dependency, the poetry2nix version is 1.31.0. Building with nix-build -A pythonPackage fails with:

RuntimeError: Building NumPy requires Cython >= 0.29.30, found 0.29.28 at /nix/store/y0b6mgmhm1vhwpsymcypr3sm64vdyj3z-python3.10-Cython-0.29.28/lib/python3.10/site-packages/Cython/__init__.py

If I explicitly add the higher cython version to the pyproject.toml, it works.