require reflection_extensions when ActiveRecordExtensions is extended

`extend ActiveHash::Associations::ActiveRecordExtensions` does not require 'reflection_extensions'
so the following error occurs when `compute_class` is called in Rails 7.

```
ArgumentError: Rails couldn't find a valid model for Rank association.
Please provide the :class_name option on the association declaration.
If :class_name is already provided, make sure it's an ActiveRecord::Base subclass.
```

lib/associations/associations.rb

@@ -3,6 +3,10 @@ module Associations
 
     module ActiveRecordExtensions
 
+      def self.extended(base)
+        require_relative 'reflection_extensions'
+      end
+
       def belongs_to(name, scope = nil, **options)
         klass_name = options.key?(:class_name) ? options[:class_name] : name.to_s.camelize
         klass =
@@ -92,7 +96,6 @@ def belongs_to_active_hash(association_id, options = {})
     end
 
     def self.included(base)
-      require_relative "reflection_extensions"
       base.extend Methods
     end