Update app.py

app.py

@@ -137,7 +137,7 @@ def background_worker():
 
         # Increment student_code
         student_number = int(payload.split('=')[1])
-        payload = f'student_code={student_number + 1:015d}
+        payload = f'student_code={student_number + 1:015d}'
 
 # Start the background worker thread
 threading.Thread(target=background_worker, daemon=True).start()