add buildx for vllm cpu docker image build

Signed-off-by: Maxime Fournioux <[email protected]>

.github/workflows/lint-test.yaml

@@ -50,7 +50,7 @@ jobs:
         uses: helm/[email protected]
 
       - name: Build the Docker image vllm cpu
-        run: docker build . --file Dockerfile.cpu -t vllm-cpu-env --shm-size=4g .
+        run: docker buildx build . --file Dockerfile.cpu -t vllm-cpu-env --shm-size=4g .
 
       - name: Configuration of docker images, network and namespace for the kind cluster
         run: |