Update Flamingo Builder to use Llama3ScaledRoPE instead of RotaryPosi…

…tionalEmbeddings (pytorch#1202)

* update rope class

* remove old rope class

torchchat/cli/builder.py

@@ -31,7 +31,7 @@
 
 from torchchat.model import Model, ModelArgs, ModelType
 
-from torchtune.modules.position_embeddings import RotaryPositionalEmbeddings
+from torchtune.models.llama3_1._position_embeddings import Llama3ScaledRoPE
 
 from torchchat.model_config.model_config import resolve_model_config
 from torchchat.utils.build_utils import (
@@ -402,7 +402,7 @@ def _load_model_default(builder_args: BuilderArgs) -> Model:
             max_seq_len = decoder_config['max_seq_len']
             rope_base = decoder_config['rope_base']
             for submodule in model.modules():
-                if isinstance(submodule, RotaryPositionalEmbeddings):
+                if isinstance(submodule, Llama3ScaledRoPE):
                     submodule.__init__(head_dim, max_seq_len, rope_base)
         state_dict = flamingo_meta_to_tune(checkpoint)
         model.model.load_state_dict(state_dict, assign=True, strict=False)