Fix an error.

model.py

@@ -30,7 +30,7 @@ def get_pretrained_model(repo_id: str) -> OfflineAsr:
     elif repo_id in english_models:
         return english_models[repo_id](repo_id)
     elif repo_id in chinese_english_mixed_models:
-        chinese_english_mixed_models[repo_id](repo_id)
+        return chinese_english_mixed_models[repo_id](repo_id)
     else:
         raise ValueError(f"Unsupported repo_id: {repo_id}")