Update currency_select.rb

Temporary fix kill 3.2.16 Rails upgrade warning... I'm sure the gem itself will be updated in the future and I won't need to add this:

I18n.config.enforce_available_locales = false

Without it gives this warning:

[deprecated] I18n.enforce_available_locales will default to true in the future. If you really want to skip validation of your locale you can set I18n.enforce_available_locales = false to avoid this message.