Upgrade Rails to version 5.2.0 (#5898)

bin/setup

@@ -1,10 +1,9 @@
 #!/usr/bin/env ruby
-require 'pathname'
 require 'fileutils'
 include FileUtils
 
 # path to your application root.
-APP_ROOT = Pathname.new File.expand_path('../../', __FILE__)
+APP_ROOT = File.expand_path('..', __dir__)
 
 def system!(*args)
   system(*args) || abort("\n== Command #{args} failed ==")