[ci] Add workflow for building NPU image (#8546)

Co-authored-by: Yaowei Zheng <hiyouga@buaa.edu.cn>

docker/docker-npu/Dockerfile

@@ -1,11 +1,12 @@
 # https://hub.docker.com/r/ascendai/cann/tags
-ARG BASE_IMAGE=ascendai/cann:8.0.0-910b-ubuntu22.04-py3.11
+ARG BASE_IMAGE=ascendai/cann:8.1.rc1-910b-ubuntu22.04-py3.11
 FROM ${BASE_IMAGE}
 
 # Installation arguments
 ARG PIP_INDEX=https://pypi.org/simple
 ARG EXTRAS=torch-npu,metrics
 ARG HTTP_PROXY=""
+ARG PYTORCH_INDEX=https://download.pytorch.org/whl/cpu
 
 # Define environments
 ENV MAX_JOBS=16
@@ -28,6 +29,10 @@ RUN pip config set global.index-url "${PIP_INDEX}" && \
     pip config set global.extra-index-url "${PIP_INDEX}" && \
     pip install --no-cache-dir --upgrade pip packaging wheel setuptools
 
+# Install torch-npu
+RUN pip uninstall -y torch torchvision torchaudio && \
+    pip install --no-cache-dir "torch-npu==2.5.1" "torchvision==0.20.1" --index-url "${PYTORCH_INDEX}"
+
 # Install the requirements
 COPY requirements.txt /app
 RUN pip install --no-cache-dir -r requirements.txt