Fix issues due to pip update and missing environment variable

[erjel]

Hi,

initially I could not install the conda environment on my own machine.

The first error message:

AttributeError: 'FileNotFoundError' object has no attribute 'read'

can be attributed to outdated syntax with respect to the requirement.txt definition.

After this initial fix I ran into a second error:

CMake Error at ${ENV_PREFIX}/share/cmake-3.21/Modules/FindPackageHandleStandardArgs.cmake:230 (message):
      Could NOT find NCCL (missing: NCCL_LIBRARY)
    Call Stack (most recent call first):
      ${ENV_PREFIX}//share/cmake-3.21/Modules/FindPackageHandleStandardArgs.cmake:594 (_FPHSA_FAILURE_MESSAGE)
      cmake/Modules/FindNCCL.cmake:42 (find_package_handle_standard_args)
      CMakeLists.txt:195 (find_package)

I figured, that this is an already known Horovod error when NCCL is installed via conda.

Minor additions include the adjustment of the CUDA version and the example of the working Horovod version.

I hope that these fixes will be useful for other folks!

Best wishes,

Eric