Issue with scipy update and find_repeats()

W_test throws error in: https://github.com/cseptesting/pycsep/blob/1c81958512f8dc08f810dd3d34d13aa0ccad17d1/csep/core/poisson_evaluations.py#L558

As of scipy version  1.17, ```scipy.stats.find_repeats()``` has been removed (https://docs.scipy.org/doc/scipy/release/1.15.0-notes.html#deprecated-features-and-future-changes). Need to change the function to ```numpy.unique()```

