You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: 20220302171443_rebake_old_avatar_service_urls.rb
    path of file: ./repos/discourse/db/migrate
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

class RebakeOldAvatarServiceUrls < ActiveRecord::Migration[6.1]
  def up
    # Only need to run this migration if 20220302163246
    # changed the site setti
    
  def up
    # Only need to run this migration if 20220302163246
    # changed the site setting. We can determine that
    # by checking for a user_histories entry in the last
    # month

    recently_changed = DB.query_single(<<~SQL).[](0)
      SELECT 1
      FROM user_histories
      WHERE action = 3
      AND subject = 'external_system_avatars_url'
      AND previous_value LIKE '%avatars.discourse.org%'
      AND created_at > NOW() - INTERVAL '1 month'
    SQL

    execute <<~SQL if recently_changed
        UPDATE posts SET baked_version = 0
        WHERE cooked LIKE '%avatars.discourse.org%'
      SQL
  end