Fix change email address

Not sure how this error creeped in 😕 probably a new gem version or
other conflicting code

The problem was we were getting an `unpermitted param email` when
updating a user’s email address

This stackoverflow solution seems to work nicely 😌
https://stackoverflow.com/questions/17384289/unpermitted-parameters-addi
ng-new-fields-to-devise-in-rails-4-0#answer-19036427

app/controllers/users/registrations_controller.rb

@@ -1,5 +1,6 @@
 class Users::RegistrationsController < Devise::RegistrationsController
   prepend_before_action :authenticate_scope!, only: [:edit, :update, :destroy, :finish_signup, :do_finish_signup]
+  before_filter :configure_permitted_parameters
 
   invisible_captcha only: [:create], honeypot: :family_name, scope: :user
 
@@ -64,6 +65,10 @@ class Users::RegistrationsController < Devise::RegistrationsController
                                    :redeemable_code)
     end
 
+    def configure_permitted_parameters
+      devise_parameter_sanitizer.for(:account_update).push(:email)
+    end
+
     def erase_params
       params.require(:user).permit(:erase_reason)
     end