[20221224] replace with pytorch cholesky

[carrtesy]

Hello,
Thanks for your code.
I've noticed an error while running your code,

According to the issue,
torch.potrf is depreciated, and can instead use torch.choelsky.

Thanks.

[liuyoude]

Hello, Thanks for your code. I've noticed an error while running your code,

According to the issue, torch.potrf is depreciated, and can instead use torch.choelsky.

Thanks.

It's what I need! Moreover, I have some other questions about test (#19 (comment)). Can you give some advice?