test(modal): increase pauses in flaky test (#6116)

* test(modal): increase pauses in flaky test

It looks like `test_modal_pop_screen()` has started being flaky in CI.

Increase the initial pause to ensure the footer is fully composed when
clicked. This seemed to be the fix for a similar flaky test in #6032.

* test(modal): wait refresh for flaky test

After increasing the pause, this test is still flaky in CI. Try adding a
`wait_for_refresh` as well, the same as the fix for a similar flaky test
in #6116

tests/test_modal.py

@@ -86,10 +86,14 @@ Button {
 async def test_modal_pop_screen():
     # https://github.com/Textualize/textual/issues/4656
 
-    async with ModalApp().run_test() as pilot:
-        await pilot.pause()
+    app = ModalApp()
+    async with app.run_test() as pilot:
+        # Pause to ensure the footer is fully composed to avoid flakiness in CI
+        await pilot.pause(0.4)
+        await app.wait_for_refresh()
         # Check clicking the footer brings up the quit screen
         await pilot.click(Footer)
+        await pilot.pause()
         assert isinstance(pilot.app.screen, QuitScreen)
         # Check activating the quit button exits the app
         await pilot.press("enter")