As the username doesn't have to be an email, having email as the type is incorrect.
This change also makes it more consistent with the way it is defined in the login form.
Can be enabled via the registration config flag. (disabled per default)
Fixesgotify/server#395
Co-authored-by: pigpig <pigpig@pig.pig>
Co-authored-by: Karmanyaah Malhotra <32671690+karmanyaahm@users.noreply.github.com>
Co-authored-by: Jannis Mattheis <contact@jmattheis.de>