Add basic AR setup to reproduction script

Many of our bug reports involve interactions between factory_bot and
active_record. This will make it easier for people to submit
reproduction scripts for those cases.

.github/REPRODUCTION_SCRIPT.rb

@@ -4,13 +4,25 @@ gemfile(true) do
   source "https://rubygems.org"
   git_source(:github) { |repo| "https://github.com/#{repo}.git" }
   gem "factory_bot", "~> 5.0"
+  gem "activerecord"
+  gem "sqlite3"
 end
 
+require "active_record"
 require "factory_bot"
 require "minitest/autorun"
+require "logger"
 
-class Post
-  attr_accessor :body
+ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
+ActiveRecord::Base.logger = Logger.new(STDOUT)
+
+ActiveRecord::Schema.define do
+  create_table :posts, force: true do |t|
+    t.string :body
+  end
+end
+
+class Post < ActiveRecord::Base
 end
 
 FactoryBot.define do