bugfix: auth-fetch: ask to never cache responses

Created by: dakkar

As the comment says, we don't want caching proxies to serve out the wrong response (thanks @ShittyCopper for reporting the problem!)

I could have factored out all the lines that set cache headers, but that would have made future merges even more complicated ☹

Checklist

• Read the contribution guide
• Test working in a local environment
• (If needed) Add story of storybook
• (If needed) Update CHANGELOG.md
• (If possible) Add tests