Registration on gitlab.c-l.net made harder

Due to the large amount of users that try to register for spam purposes we've had to make registration (and login via Google) a bit harder.

One step more

Please message minion on #common-lisp.net on Libera IRC about the registration URL; you can either use your own IRC client, or use webchat need to "Auth to services").

The right question would be the string minion: registration, please?; you'll receive answer in near-realtime.

The URL you receive can be used both for registration, as well as for logging in via Google; if you already have a local user or use GitHub, these restrictions do not (yet) apply.