[BUG] - L2 norm missing square root in AverageStability

[carreremax]

Select the modules to which the bug refers:
Metrics

Describe the bug
L2 norm is missing square root in AverageStability.

l.56-57 of stability.py :
elif distance == 'l2':
self.distance = lambda x, y: tf.reduce_sum((x-y)**2.0)

Desktop (please complete the following information):
Windows

To Reproduce
You can check the difference between L1 et L2 explanation when the explanations values are high.
My explanations were for an image (512,512), with maximum of 2400 and average of 25.
On theses explanations :

• Average stability with L1 norm outputs a value per pixel of around 16.7.
• Average stability with L2 norm outputs a value per pixel of more than 1800.

Expected behavior
Sqrt added to the L2 norm.