title: Failed on Migration using Paperclip on Rails
body: <p>I am trying to install Paperclip using Rails 6.1</p>
  <p>I ran this command : <code>rails g paperclip Model image</code></p>
  <p>And i got this migration :</p>
  <pre><code>class AddAttachmentImageToExercises &lt; ActiveRecord::Migration
    def self.up
      change_table :exercises do |t|
        t.attachment :image
      end
    end
  
    def self.down
      remove_attachment :exercises, :image
    end
  end
  </code></pre>
  <p>But i got this error :</p>
  <pre><code>Caused by:
  StandardError: Directly inheriting from ActiveRecord::Migration is not supported. Please specify the Rails release the migration was written for:
  </code></pre>
  <p>Then i put class AddAttachmentImageToExercises &lt; ActiveRecord::Migration[6.1]
  I got this error :</p>
  <pre><code>ArgumentError: wrong number of arguments (given 3, expected 2)
  </code></pre>
  <p>What should i do? Thank You</p>