Compatibility with matplotlib 3.10

[xumi1993]

def ci(allstack, h, kappa, ev_num):
        """
        Search best H and kappa from stacked matrix.
        Calculate error for H and kappa
    
        :param allstack: stacked HK matrix
        :param h: 1-D array of H
        :param kappa: 1-D array of kappa
        :param ev_num: event number
        :return:
        """
        [i, j] = np.unravel_index(allstack.argmax(), allstack.shape)
        bestk = kappa[i]
        besth = h[j]
    
        cvalue = 1 - np.std(allstack.reshape(allstack.size)) / np.sqrt(ev_num)
        cs = plt.contour(h, kappa, allstack, [cvalue])
>       cs_path = cs.collections[0].get_paths()[0].vertices
E       AttributeError: 'QuadContourSet' object has no attribute 'collections'

This error will be raised when using matplotlib 3.10. using

 cs_path = cs.get_paths()[0].vertices

instead in the future version.