Teardown the app (context), calling the teardown functions.

async def do_teardown_appcontext(self, exc: Optional[BaseException]) -> None:
        """Teardown the app (context), calling the teardown functions."""
        for function in self.teardown_appcontext_funcs:
            await function(exc)
        await appcontext_tearing_down.send(self, exc=exc)