In Grav 1.7, admin must follow http_x_forwarded

With 1.7 I'm getting a reroll of https://github.com/getgrav/grav/issues/1095 / https://github.com/getgrav/grav-plugin-admin/issues/1981 where, after a successful login, I'm redirected to:
`:/admin` instead of `:/admin`

In Grav 1.7 I have to set `http_x_forwarded.port: false` to fix the routing for pages redirects doesn't keeps the `admin` plugin from mis-redirecting.