Gemfile in tdiary-5.2.3 vs Gemfile in tdiary-5.2.4

@@ -1,7 +1,8 @@
 source 'https://rubygems.org'
 
 gem 'rack'
+gem 'rackup'
 gem 'hikidoc'
 gem 'fastimage'
 gem 'emot'
 gem 'mail'
 gem 'net-smtp' # https://github.com/mikel/mail/pull/1439