Update Cython files to `numpy>2.0` typing

The new `cosmodesi` environment now has `numpy>2` which can cause some typing issues in the Cython compiled files.

This was hotfixed first by enforcing `numpy<2.0` in the `pyproject.toml` and then with a fix (#129) from @PalPaulD and seems to work for now.

In the future, it would be nice to have some more permanent fix.