Regularized H-Score and TransRate

[Tech-Netiums]

I added two recent transferability metrics :

• An improved version of H-Score using LedoitWolf covariance estimator from Newer is not always better: Rethinking transferability metrics, their peculiarities, stability and performance
• TransRate from Frustratingly easy transferability estimation

I also replaced the manual computation of covariance by the numpy version which is much faster. I added the regularized H_score to the H-Score scipt but I can make two different scripts