Notifications intermittent test failure

[b4handjr]

I've seen this error a few times, we should probably make this property a bit more robust.

=================================== FAILURES ===================================
___________ test_progress_notification_downloading[firefox_options0] ___________

browser = <foxpuppet.windows.browser.window.BrowserWindow object at 0x7f221c31ff50>
progress_notification = <foxpuppet.windows.browser.notifications.addons.AddOnProgress object at 0x7f221c3e1ee0>

    @pytest.mark.parametrize(
        "firefox_options", [{"page_load_strategy_none": True}], indirect=True
    )
    def test_progress_notification_downloading(
        browser: BrowserWindow, progress_notification: AddOnProgress
    ) -> None:
        """Verify downloading status is reported correctly."""
        description = progress_notification.is_downloading
>       assert description is True
E       assert False is True