[BC breaking change in torch] weights_only default flip for torch.load

[mikaylagawarecki]

We've flipped the default for the weights_only argument in torch.load to True in pytorch/pytorch, see here for details + documentation and this is coming in torch 2.6.

This is expected to be quite a BC-breaking change, especially if any torch.load calls are not loading state_dicts of plain tensors.

We should make sure that all the torch.load calls in captum are still working. I see 11 of them that don't have weights_only set (mostly in tutorials).

I'm happy to open a PR to explicitly set weights_only on these, but not sure who to ping for review