Use empty dict instead of none to load only metadata from dist ckpt

due to change in mcore commit NVIDIA/Megatron-LM@31e8bfa

Signed-off-by: Chen Cui <[email protected]>

nemo/lightning/pytorch/callbacks/peft.py

@@ -448,7 +448,7 @@ def load_checkpoint(
         if getattr(path, "base_model_path", None):
             ## PEFT Resume, FIRST TIME
             self.adapter_ckpt_path = Path(str(path))
-            adapter_ckpt = self.checkpoint_io.load_checkpoint(path)  # Loads only metadata
+            adapter_ckpt = self.checkpoint_io.load_checkpoint(path, sharded_state_dict={})  # Loads only metadata
             # path is adapter path to restore the training metadata, but switch to loading base model here.
             path = self.model_ckpt_path = path.base_model_path
         elif adapter_meta_path.exists():