tests: Partially refactor test_show_typing_notification to fix flaky behavior caused by asynchronous timing. Fixes #1501.

Author: kkieu

tests/core/test_core.py

@@ -1,7 +1,7 @@
 import os
 import webbrowser
 from platform import platform
-from threading import Thread, Timer
+from threading import Thread
 from typing import Any, Dict, List, Optional, Set, Tuple
 
 import pyperclip