Pin Windows CUDA cross-compile back to 12.6

Reverts the Windows side of 8757b66; Linux CUDA matrix is unchanged.
The 12.6 entry in CUDA_DRIVER_MAP is already valid, so no change to
install_cuda_windows_cross_compile.sh is required.

Authored with Claude.

Author: mergennachin

.ci/docker/build.sh

@@ -80,7 +80,7 @@ case "${IMAGE_NAME}" in
     LINTRUNNER=""
     GCC_VERSION=11
     CUDA_WINDOWS_CROSS_COMPILE=yes
-    CUDA_VERSION=13.0
+    CUDA_VERSION=12.6
     SKIP_PYTORCH=yes
     ;;
   *)

.github/workflows/cuda-windows.yml

@@ -64,7 +64,7 @@ jobs:
       secrets-env: EXECUTORCH_HF_TOKEN
       runner: linux.g5.4xlarge.nvidia.gpu
       gpu-arch-type: cuda
-      gpu-arch-version: 13.0
+      gpu-arch-version: 12.6
       docker-image: ci-image:executorch-ubuntu-22.04-cuda-windows
       submodules: recursive
       upload-artifact: ${{ matrix.model_repo }}-${{ matrix.model_name }}-cuda-windows-${{ matrix.quant }}
@@ -146,7 +146,7 @@ jobs:
       timeout: 240
       runner: windows.g5.4xlarge.nvidia.gpu
       gpu-arch-type: cuda
-      gpu-arch-version: 13.0
+      gpu-arch-version: 12.6
       download-artifact: ${{ matrix.model_repo }}-${{ matrix.model_name }}-cuda-windows-${{ matrix.quant }}
       ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
       script: |
@@ -158,7 +158,7 @@ jobs:
           \$ErrorActionPreference = 'Stop'
           \$PSNativeCommandUseErrorActionPreference = \$true
 
-          \$env:CUDA_HOME = 'C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v13.0'
+          \$env:CUDA_HOME = 'C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v12.6'
           \$env:CUDA_PATH = \$env:CUDA_HOME
           \$env:PATH = \"\$env:CUDA_HOME\bin;\$env:PATH\"
           nvcc --version
@@ -169,5 +169,5 @@ jobs:
             throw 'RUNNER_ARTIFACT_DIR is empty. Ensure download-artifact is configured for windows_job.yml.'
           }
 
-          .ci/scripts/test_model_e2e_windows.ps1 -Device cuda-windows -HfModel '${{ matrix.model_repo }}/${{ matrix.model_name }}' -QuantName '${{ matrix.quant }}' -ModelDir \$artifactDir -ExpectedCudaVersion '13.0'
+          .ci/scripts/test_model_e2e_windows.ps1 -Device cuda-windows -HfModel '${{ matrix.model_repo }}/${{ matrix.model_name }}' -QuantName '${{ matrix.quant }}' -ModelDir \$artifactDir -ExpectedCudaVersion '12.6'
         }"