Add missing require for dev_seeds rake task spec

spec/lib/tasks/dev_seed_spec.rb

@@ -1,5 +1,7 @@
-require 'rails_helper'
 require 'rake'
+require 'rails_helper'
+Rake::Task.define_task(:environment)
+Rake.application.rake_require('tasks/db')
 
 describe 'rake db:dev_seed' do
   let :run_rake_task do