allow newer grape-entity already in debian

Index: gitlab/Gemfile
===================================================================
--- gitlab.orig/Gemfile
+++ gitlab/Gemfile
@@ -68,7 +68,7 @@ gem 'github-linguist', '~> 4.7.0', requi
 
 # API
 gem 'grape',        '~> 0.15.0'
-gem 'grape-entity', '~> 0.4.2'
+gem 'grape-entity', '~> 0.5.0'
 gem 'rack-cors',    '~> 0.4.0', require: 'rack/cors'
 
 # Pagination