Add numpy>=2 support

[braniii]

@gegabo the action is failing due to sklearn_extra which does not support numpy>=2. Should we (or better you) switch to the https://github.com/kno10/python-kmedoids package instead, or deprecating the k-medoids functionality completely. Leiden outperforms k-medoids anyway. What do you think?

[gegabo]

I am in favor of removing k-medoids altogether, since python-kmedoids is not a standard dependency