[CI] Add SM120 to the Dockerfile (vllm-project#19794)

Signed-off-by: mgoin <mgoin64@gmail.com>

Author: mgoin

docker/Dockerfile

@@ -77,7 +77,7 @@ RUN --mount=type=cache,target=/root/.cache/uv \
 # can be useful for both `dev` and `test`
 # explicitly set the list to avoid issues with torch 2.2
 # see https://github.com/pytorch/pytorch/pull/123243
-ARG torch_cuda_arch_list='7.0 7.5 8.0 8.9 9.0 10.0+PTX'
+ARG torch_cuda_arch_list='7.0 7.5 8.0 8.9 9.0 10.0 12.0'
 ENV TORCH_CUDA_ARCH_LIST=${torch_cuda_arch_list}
 # Override the arch list for flash-attn to reduce the binary size
 ARG vllm_fa_cmake_gpu_arches='80-real;90-real'
@@ -244,7 +244,7 @@ RUN --mount=type=bind,from=build,src=/workspace/dist,target=/vllm-workspace/dist
 
 # If we need to build FlashInfer wheel before its release:
 # $ # Note we remove 7.0 from the arch list compared to the list below, since FlashInfer only supports sm75+
-# $ export TORCH_CUDA_ARCH_LIST='7.5 8.0 8.9 9.0a 10.0a'
+# $ export TORCH_CUDA_ARCH_LIST='7.5 8.0 8.9 9.0a 10.0a 12.0'
 # $ git clone https://github.com/flashinfer-ai/flashinfer.git --recursive
 # $ cd flashinfer
 # $ git checkout v0.2.6.post1
@@ -261,7 +261,7 @@ if [ "$TARGETPLATFORM" != "linux/arm64" ]; then \
     if [[ "$CUDA_VERSION" == 12.8* ]]; then \
         uv pip install --system https://download.pytorch.org/whl/cu128/flashinfer/flashinfer_python-0.2.6.post1%2Bcu128torch2.7-cp39-abi3-linux_x86_64.whl; \
     else \
-        export TORCH_CUDA_ARCH_LIST='7.5 8.0 8.9 9.0a 10.0a' && \
+        export TORCH_CUDA_ARCH_LIST='7.5 8.0 8.9 9.0a 10.0a 12.0' && \
         git clone https://github.com/flashinfer-ai/flashinfer.git --single-branch --branch v0.2.6.post1 --recursive && \
         # Needed to build AOT kernels
         (cd flashinfer && \