Merge pull request solidusio#201 from brchristian/patch-1

Update migrations to support Rails 5.1

db/migrate/20200417153503_add_unconfirmed_email_to_spree_users.rb

@@ -1,4 +1,4 @@
-class AddUnconfirmedEmailToSpreeUsers < ActiveRecord::Migration[5.2]
+class AddUnconfirmedEmailToSpreeUsers < SolidusSupport::Migration[5.1]
   def change
     unless column_exists?(:spree_users, :unconfirmed_email)
       add_column :spree_users, :unconfirmed_email, :string