gitlab: fix inconsistent indentation

The standard is to use 2 space indent, not 3.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210216132954.295906-4-berrange@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>