ci: enable gfx90c for nightly PyTorch builds (#7242)

## Motivation

Enable gfx90c torch nightly builds.

Relates to #6805

## Technical Details

Upstream PyTorch nightly branch now pins
https://github.com/ROCm/composable_kernel/tree/5a74dec07a894484b9489d0c0e00cd3b52652d18
which includes gfx90c support resolving any of the
`CK_BUFFER_RESOURCE_3RD_DWORD undeclared for gfx90c` errors we were
guarding against.

## Test Plan

https://github.com/ROCm/TheRock/actions/runs/31419258422/job/93555777554

## Test Result

Expected - Nightly torch build pass on gfx90c.

## Submission Checklist

- [X] Look over the contributing guidelines at
https://github.com/ROCm/TheRock/blob/main/CONTRIBUTING.md.

Author: harkgill-amd

build_tools/github_actions/configure_pytorch_release_matrix.py

@@ -64,8 +64,7 @@
         # gfx125x supported for PyTorch 2.13 via https://github.com/ROCm/pytorch/pull/3532.
         "release/2.13": {"gfx90c"},
         # gfx125x supported on upstream pytorch/pytorch nightly via pytorch#188597.
-        # gfx90c excluded: blocked until CK submodule bump in pytorch nightly.
-        "nightly": {"gfx90c"},
+        "nightly": {},
     },
     "windows": {
         "release/2.11": {"gfx90c"},