fix document loader

app.py

@@ -243,7 +243,7 @@ def respond(
   
 def upload_documents(files):  
     for file in files:  
-        loader = DocumentLoader(file.name)  
+        loader = UnstructuredFileLoader(file.name)  
         documents = loader.load_documents()  
         chroma_manager.add_documents(documents)  
     return "Documents uploaded and processed successfully!"