Remove unsupported Rails AR code.

Gemfile.mongo_mapper

@@ -1,9 +1,9 @@
 eval_gemfile('Gemfile.global')
 
 gem 'minitest', '~> 5.8'
-gem 'rails',    github: 'rails/rails', branch: '7-0-stable', require: false
+gem 'rails',    github: 'rails/rails', branch: '7-2-stable', require: false
 gem 'mongo_mapper'
 
 # This Rails version has a pessimistic version constraint on sqlite3:
-# https://github.com/rails/rails/blob/7-0-stable/Gemfile#L148
+# https://github.com/rails/rails/blob/7-2-stable/Gemfile#L160
 gem 'sqlite3', '~> 1.6', '>= 1.6.6', platforms: [:ruby, :mswin, :mingw]

lib/enumerize/activerecord.rb

@@ -21,20 +21,10 @@ def enumerize(name, options={})
           require 'enumerize/hooks/uniqueness'
 
           unless options[:multiple]
-            if ::ActiveRecord.version >= ::Gem::Version.new("7.2.0.alpha")
-              attribute(name)
+            attribute(name)
 
-              decorate_attributes([name]) do |_, subtype|
-                Type.new(enumerized_attributes[name], subtype)
-              end
-            elsif ::ActiveRecord.version >= ::Gem::Version.new("7.0.0.alpha")
-              attribute(name) do |subtype|
-                Type.new(enumerized_attributes[name], subtype)
-              end
-            else
-              decorate_attribute_type(name, :enumerize) do |subtype|
-                Type.new(enumerized_attributes[name], subtype)
-              end
+            decorate_attributes([name]) do |_, subtype|
+              Type.new(enumerized_attributes[name], subtype)
             end
           end
         end