replace cached_find_by with find_by_cached on Spree::Country

In version 7.1, find_by (active record method) call cached_find_by.
https://github.com/rails/rails/blob/1ea796d6a887ddb6fd7a2395399ae35871aeb00c/activerecord/lib/active_record/core.rb#L246-L257
we rename our method to avoid collision

app/models/spree/country.rb

@@ -6,7 +6,7 @@ class Country < ApplicationRecord
 
     validates :name, :iso_name, presence: true
 
-    def self.cached_find_by(attrs)
+    def self.find_by_cached(attrs)
       Rails.cache.fetch("countries/#{attrs.hash}", expires_in: 1.hour) do
         find_by(attrs)
       end

app/services/default_country.rb

@@ -10,7 +10,7 @@ def self.code
   end
 
   def self.country
-    Spree::Country.cached_find_by(iso: ENV.fetch("DEFAULT_COUNTRY_CODE",
+    Spree::Country.find_by_cached(iso: ENV.fetch("DEFAULT_COUNTRY_CODE",
                                                  nil)) || Spree::Country.first
   end
 end