Function set_email_verified 

pub async fn set_email_verified(
    conn: &mut PgConnection,
    user_id: Uuid,
    method: EmailVerificationMethod,
    verified_at: DateTime<Utc>,
) -> ModelResult<()>

Records a proof of control over the address currently in email.

Must not also write email: the clear_email_verification trigger would null the flag in the same statement.