refactor(tests): Add strict type hints to fifth batch of test files

tests/test_gui_events.py

@@ -1,13 +1,14 @@
 
 import pytest
 from unittest.mock import MagicMock, patch
+from typing import Generator
 import dearpygui.dearpygui as dpg
 import gui_legacy
 from gui_legacy import App
 import ai_client
 
 @pytest.fixture
-def app_instance() -> None:
+def app_instance() -> Generator[App, None, None]:
  """
     Fixture to create an instance of the App class for testing.
     It creates a real DPG context but mocks functions that would
@@ -33,8 +34,7 @@ def app_instance() -> None:
   yield app
  dpg.destroy_context()
 
-def test_gui_updates_on_event(app_instance):
-# Patch dependencies for the test
+def test_gui_updates_on_event(app_instance: App) -> None:
  with patch('dearpygui.dearpygui.set_value') as mock_set_value, \
  patch('dearpygui.dearpygui.does_item_exist', return_value=True), \
  patch('dearpygui.dearpygui.configure_item'), \