Add MI300.2 GPU to Torchao CI (#1878)

Update ROCM nightly workflow to use MI300.2 GPU configuration

Author: petrex

.github/workflows/regression_test_rocm.yml

@@ -21,7 +21,7 @@ jobs:
       matrix:
         include:
           - name: ROCM Nightly
-            runs-on: linux.rocm.gpu.torchao
+            runs-on: linux.rocm.gpu.mi300.2
             torch-spec: '--pre torch==2.7.0.dev20250122 --index-url https://download.pytorch.org/whl/nightly/rocm6.3'
             gpu-arch-type: "rocm"
             gpu-arch-version: "6.3"