Fixes the error 'Your email wasn't updated' when idpattr

[sumaiyamannan]

This fixes the reported https://github.com/catalyst/moodle-auth_saml2/issues/728 saml2 settings used:

field_updatelocal_email: on every login idpattr: email mdlattr: email address autocreate: yes field_map_username: email

I have tested this on a Moodle 3.9 site. Regards,

Sumaiya