Added support for uppercase letters in torch.einsum (#56475)
Summary:
This PR adds support for upper case letters in `torch.einsum` equation.
Addresses PR https://github.com/pytorch/pytorch/pull/55013 here.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/56475
Reviewed By: ailzhang
Differential Revision: D27948362
Pulled By: heitorschueroff
fbshipit-source-id: 51cf57b17c4c23d88fab5343f17ba3bfbe3607a5
