Make sure to load rails before loading haml

Or haml/railtie will not be required.

This normally will be done inside haml-rails for the users' apps, but since
we're not depending on haml-rails in this repo to avoid mutual dependency,
we need to carefully craft the gem load order here.

test/test_helper.rb

@@ -13,7 +13,6 @@ if ENV["COVERAGE"]
 end
 
 require 'bundler'
-Bundler.require(:default)
 require 'minitest/autorun'
 require 'action_pack'
 require 'action_controller'
@@ -21,6 +20,7 @@ require 'action_view'
 require 'action_view/base'
 require 'nokogiri'
 require 'rails'
+Bundler.require(:default)
 
 if defined?(I18n.enforce_available_locales)
   I18n.enforce_available_locales = true