fix: Fix IndexError resulting from cumsum(fractions)[-1] != 1

[adigitoleo]

This fixes an occasional IndexError that occurs during resampling, if np.cumsum(fractions_ascending) < rng.random(), which results in np.searchsorted() returning an index outside the size of the new arrays.

[adigitoleo]

From the np.cumsum docs:

cumsum(a)[-1] may not be equal to sum(a) for floating-point values since sum may use a pairwise summation routine, reducing the roundoff-error. See sum for more information.