updated deprecated ssm/ path

Signed-off-by: Oded Ovadia <oded7272@gmail.com>

Author: odedovadia

src/megatron/bridge/training/utils/train_utils.py

@@ -25,7 +25,7 @@
 import torch
 import torch.nn as nn
 from megatron.core.num_microbatches_calculator import get_num_microbatches
-from megatron.core.ssm.mamba_hybrid_layer_allocation import Symbols
+from megatron.core.models.hybrid.hybrid_layer_allocation import Symbols
 from megatron.core.tensor_parallel import param_is_not_tensor_parallel_duplicate
 from megatron.core.transformer.module import MegatronModule
 from megatron.core.transformer.moe.moe_utils import track_moe_metrics