Add CMake policy for legacy code

Author: mc-nv

qa/L0_backend_python/common.sh

@@ -86,6 +86,7 @@ create_python_backend_stub() {
   rm -rf python_backend
   git clone ${TRITON_REPO_ORGANIZATION}/python_backend -b $PYTHON_BACKEND_REPO_TAG
   CUDA_PATH=$(readlink -f /usr/local/cuda)
+  export CMAKE_POLICY_VERSION_MINIMUM=3.5
   (cd python_backend/ && mkdir builddir && cd builddir && \
   cmake -DTRITON_ENABLE_GPU=ON -DCMAKE_CUDA_COMPILER=$CUDA_PATH/bin/nvcc \
      -DCUDAToolkit_ROOT=$CUDA_PATH -DTRITON_REPO_ORGANIZATION:STRING=${TRITON_REPO_ORGANIZATION} \