Update app.py

app.py

@@ -150,7 +150,7 @@ def retrieve_document(query):
     pdf_file = requests.get(API_URL_FILES, filename)
 
     # Read and return the document content
-    with open(filename, "r", encoding="utf-8") as f:
+    with open(pdf_file, "r", encoding="utf-8") as f:
         return f.read()
 
 def clean_text(text):