Warnings are not treated as errors in the tests #279
Description
with @PicoCentauri we noticed that the function _FPS of skmatter._selection broke the metatrain CI becouse of some deprecationWarning. The same warnings are also in the skmatter CI, but here they are not treated as errors in the CI.
For the error in metatrain see metatensor/metatrain#989, the warning is:
/home/runner/work/scikit-matter/scikit-matter/src/skmatter/_selection.py:1166: DeprecationWarning: Passing more than 2 positional arguments to np.maximum and np.minimum is deprecated. If you meant to use the third argument as an output, use the `out` keyword argument instead. If you hoped to work with more than 2 inputs, combine them into a single array and get the extrema for the relevant axis. np.minimum(self.hausdorff_, new_dist, self.hausdorff_)