Create conda template for GPU dependencies.

[trivialfis]

We can use a jinja template to avoid:

    mamba create -y -n gpu_test -c rapidsai -c conda-forge -c nvidia \
        python=$PYTHON_VERSION "cudf=$RAPIDS_VERSION.*" "rmm=$RAPIDS_VERSION.*" cuda-version=$CUDA_SHORT_VER \
        "nccl=${NCCL_SHORT_VER}" \
        dask \
        distributed \
        "dask-cuda=$RAPIDS_VERSION.*" "dask-cudf=$RAPIDS_VERSION.*" cupy \
        numpy pytest pytest-timeout scipy scikit-learn pandas matplotlib wheel \
        python-kubernetes urllib3 graphviz hypothesis "loky>=3.5.1" \
        "pyspark>=3.4.0,<4.0" cloudpickle cuda-python && \