Update regression_test.yml (#1163)

Author: jcaip

.github/workflows/regression_test.yml

@@ -40,7 +40,7 @@ jobs:
             gpu-arch-version: "12.1"
           - name: CUDA Nightly
             runs-on: linux.g5.12xlarge.nvidia.gpu
-            torch-spec: '--pre torch --index-url https://download.pytorch.org/whl/nightly/cu121'
+            torch-spec: '--pre torch==2.6.0.dev20241022 --index-url https://download.pytorch.org/whl/nightly/cu121'
             gpu-arch-type: "cuda"
             gpu-arch-version: "12.1"