Selfhosted Gitlab SSO

I just replaced the URL https://gitlab.com in the hybridauth/library/src/Provider/GitLab.php with another one and it worked.

So all you need is an input field in the admin interface where you can enter your own gitlab URL. Then you can also use a self-hosted Gitlab instance.