Mark entire CudaTest class as requiring docker

[cottsay]

The call to get_docker_client in setUpClass will fail if docker is not available on the host.

Resolves:

test/test_nvidia.py:256: in setUpClass
    client = get_docker_client()
../../install_isolated/rocker/lib/python3.12/site-packages/rocker/core.py:220: in get_docker_client
    raise DependencyMissing('Docker Client failed to connect to docker daemon.'
E   rocker.core.DependencyMissing: Docker Client failed to connect to docker daemon. Please verify that docker is installed and running. As well as that you have permission to access the docker daemon. This is usually by being a member of the docker group. The underlying error was:
E   """
E   Error while fetching server API version: ('Connection aborted.', FileNotFoundError(2, 'No such file or directory'))
E   """

[tfoote]

Thanks, yeah the invocation of get_docker_client in the setUpClass does require that now.