Add PyTorch 2.9 to CI Test Matrix

[mhs4670go]

What

We currently run CI against PyTorch 2.5, 2.6, 2.7, and 2.8.

Since PyTorch 2.9 has now been released, we should extend our CI matrix to include 2.9 to ensure forward compatibility and catch regressions early.

This is especially important because our project depends on PyTorch internals, which tend to change across minor releases.

[dayo09]

NOTE: pytorch 2.10 Release date: 21th Jan

11/07 UPDATE: Please note that the M2 to M4 dates below have changed, and release day will now be Jan 21st 2026.

https://github.com/pytorch/pytorch/milestone/57

They've set v2.10 release date as 21th Jan. That's pretty soon.
When someone work on this job, it could be covered at once for convenience.