Fix vllm nccl sync error (#132)

Author: pan-x-c

trinity/trainer/verl/fsdp_workers.py

@@ -27,8 +27,7 @@
 import torch
 import torch.distributed
 import torch.distributed as dist
-
-# import vllm  # noqa: F401 ; import vllm to set NCCL_CUMEM_ENABLE automatically.
+import vllm  # noqa: F401 ; import vllm to set NCCL_CUMEM_ENABLE automatically.
 from codetiming import Timer
 from omegaconf import DictConfig, OmegaConf, open_dict
 from peft import LoraConfig, TaskType, get_peft_model