y = np.array([2.40407, 1.588134, 1.760112, 1.77136, 1.860087, 1.955789, 
    1.910408, 1.655911, 1.778952, 2.624719, 1.698099, 3.022607, 3.303135])
xx = np.arange(1, 13.01, 0.1)
Fitting data using UnivariateSpline in scipy python