add default values

Author: ZhaoyangHan04

dataflow/operators/generate/KnowledgeCleaning/file_or_url_to_markdown_converter.py

@@ -157,8 +157,8 @@ class FileOrURLToMarkdownConverter(OperatorABC):
     """
     def __init__(
         self, 
-        url,
-        raw_file,
+        url: str = None,
+        raw_file: str = None,
         intermediate_dir: str = "intermediate", 
         lang: str = "en", 
         mineru_backend:  Literal["vlm-sglang-engine", "pipeline"] = "vlm-sglang-engine",