fix spelling mistake (#749)

deepspeed/runtime/fp16/onebit_adam.py

@@ -362,7 +362,7 @@ class OnebitAdam(torch.optim.Optimizer):
             self.adam_freeze_key = False
             self.initialize = True
             print(
-                f"Finished the initialization step at rant {torch.distributed.get_rank()}"
+                f"Finished the initialization step at rank {torch.distributed.get_rank()}"
             )
             return loss