@keystone-6/auth Open Redirect vulnerability

Keystone is a content management system for Node.JS. There is an open redirect in the `@keystone-6/auth` package versions 7.0.0 and prior, where the redirect leading `/` filter can be bypassed. Users may be redirected to domains other than the relative host, thereby it might be used by attackers to re-direct users to an unexpected location. To mitigate this issue, one may apply a patch from pull request 8626 or avoid using the `@keystone-6/auth` package.