fix qwen3 embedding saving (#4548)

---------

Co-authored-by: tastelikefeet <[email protected]>

Author: tastelikefeet

swift/trainers/mixin.py

@@ -223,6 +223,11 @@ def _save_model(self, output_dir: Optional[str] = None, state_dict=None):
         else:
             if self.model.__class__.__name__ != 'SentenceTransformer':
                 self.model.save_pretrained(output_dir, state_dict=state_dict, safe_serialization=save_safetensors)
+                # For embedding models, they should copy extra sentence_transformers files
+                from swift.utils import copy_files_by_pattern
+                copy_files_by_pattern(self.model.model_dir, output_dir, 'config_sentence_transformers.json')
+                copy_files_by_pattern(self.model.model_dir, output_dir, '1_Pooling/config.json')
+                copy_files_by_pattern(self.model.model_dir, output_dir, 'modules.json')
             else:
 
                 @contextmanager