Avoid random failures in test (#624)

Negative weights can give errors.

Author: nalimilan

test/moments.jl

@@ -104,8 +104,8 @@ expected_std = sqrt.(expected_var)
 end
 
 x = rand(5, 6)
-w1 = rand(5)
-w2 = rand(6)
+w1 = [0.57, 5.10, 0.91, 1.72, 0.0]
+w2 = [3.84, 2.70, 8.29, 8.91, 9.71, 0.0]
 
 @testset "Uncorrected with $f" for f in weight_funcs
     wv1 = f(w1)