Fix a warning from rails

```
config.eager_load is set to nil. Please update your config/environments/*.rb files accordingly:

  * development - set it to false
  * test - set it to false (unless you use a tool that preloads your test environment)
  * production - set it to true
````

spec/helper.rb

@@ -38,6 +38,7 @@
 ENV['RAILS_ENV'] = 'test'
 
 FakeApp = Class.new(Rails::Application)
+FakeApp.config.eager_load = false
 
 Delayed::Worker.backend = :test