Update submodule NCCL to v2.18.3 (#104993)
Update NCCL submodule to v2.18.3 which fixes numerous bugs and performance issues, particularly on newer GPUs: https://docs.nvidia.com/deeplearning/nccl/release-notes/rel_2-18-3.html#rel_2-18-3
Pull Request resolved: https://github.com/pytorch/pytorch/pull/104993
Approved by: https://github.com/malfet
