chore: Fix latest lint offences

Three easy, peasy ones

Author: tvdeyen

core/app/models/spree/stock/estimator.rb

@@ -64,7 +64,7 @@ def shipping_methods(package)
             calculator.available?(package) &&
               (calculator.preferences[:currency].blank? ||
                calculator.preferences[:currency] == package.shipment.order.currency)
-        end
+          end
       end
     end
   end

core/app/models/spree/store.rb

@@ -47,7 +47,7 @@ def available_locales=(locales)
       if locales.empty?
         super(nil)
       else
-        super(locales.map(&:to_s).join(","))
+        super(locales.join(","))
       end
     end
 

core/app/models/spree/variant/pricing_options.rb

@@ -101,7 +101,7 @@ def country_iso
       # @return [String] cache key to be used in views
       #
       def cache_key
-        desired_attributes.values.select(&:present?).map(&:to_s).join("/")
+        desired_attributes.values.select(&:present?).join("/")
       end
     end
   end