Add support for NumPy 2.0

[huard]

The current version is incompatible with NumPy 2.0, both the latest release and a local installation.

Specifically, it crashes with

../../.conda/envs/ing11/lib/python3.11/site-packages/copulae-0.7.9-py3.11-linux-x86_64.egg/copulae/archimedean/frank.py:240: in debye1
    x = np.asarray(x, np.float_).ravel()
...
AttributeError: `np.float_` was removed in the NumPy 2.0 release. Use `np.float64` instead