Update PyTorch commit pin.

[ysiraichi]

This PR updates the PyTorch pin to the head of PyTorch viable/strict branch (2025-11-04).
This update should unblock 2 PRs that need an updated version of PyTorch:

• implement XLAHooks and register it to PyTorch when loaded. #9683
  • Needs pytorch/pytorch@defb6a8 (merged in 2025-10-23)
• Remove fmtlib explicit dependency. #9702
  • Needs pytorch/pytorch@089f913 (merged in 2025-09-29)
  • Already unblocked, since the pinned .torch_commit is using fmtlib version 11.2.0 (not 12.0.0)

[ysiraichi]

This will take longer than I previously anticipated. So, I'm letting this go until we really need it.
For whoever takes this on:

I was able to understand why some svd tests are failing.
Because of pytorch/pytorch#164939, PyTorch stopped registering CompositeImplicitAutograd kernels to the Functionalize dispatch-key. In summary, this means that we can now create kernels for them. The svd operation is one of them. The problem is that we already have an svd kernel. Which means that it will get called instead of the CompositeImplicitAutograd kernel (which called _linalg_svd).

Feel free to re-open this if needed.