fix app.py error

app.py

@@ -18,8 +18,7 @@ except Exception as e:
 def retrieve(
     query: str, 
     collection_name: str =None,
-    top_level_filter: str = None,
-    top_level_filter_value:str|list = None
+    filter_metadata:list[dict] = None,
 ) -> list:
     """
     Retrieve semantically similar documents from the vector database for MCP clients.