[Tests] Test attention class

[patrickvonplaten]

Test attention class: https://github.com/huggingface/diffusers/blob/main/src/diffusers/models/attention.py

We should test this class well

[rashmimarganiatgithub]

@patrickvonplaten , And this also please assign to me?

[patrickvonplaten]

Sure :-) Feel free to open a PR for it and others that are interested can directly jump in

[sidthekidder]

I started a PR for this issue. Hope @rashmimarganiatgithub doesn't mind me jumping in, I was looking for an easier testing issue!

[rashmimarganiatgithub]

@sidthekidder , Please go ahead. I will take other issues.

[sayakpaul]

Closing because of #368