覆盖Contao缓存标头

In my Contao 4.6 I want to overwrite the Cache header but couldnt find a place where I can overwrite it. When I put my snippet into web/app.php it will be overwritten everytime I run composer install or do a update

I have put this snippet into web/app.php which worked, but this file will be overwritten after every update I am not wrong.

$response->headers->set('Cache-Control', 'public');