Fixed deepcopy failure when passing llm_client (#1089)

Co-authored-by: afourney <adamfo@microsoft.com>

packages/markitdown/src/markitdown/_markitdown.py

@@ -455,7 +455,7 @@ class MarkItDown:
                     cur_pos == file_stream.tell()
                 ), f"File stream position should NOT change between guess iterations"
 
-                _kwargs = copy.deepcopy(kwargs)
+                _kwargs = {k:v for k,v in kwargs.items()}
 
                 # Copy any additional global options
                 if "llm_client" not in _kwargs and self._llm_client is not None: