Upgrade grape-entity

Fixes gitlab-org/gitlab-ce#14329

Gemfile

@@ -68,7 +68,7 @@ gem 'github-linguist', '~> 4.7.0', require: 'linguist'
 
 # API
 gem 'grape',        '~> 0.15.0'
-gem 'grape-entity', '~> 0.4.2'
+gem 'grape-entity', '~> 0.5.2'
 gem 'rack-cors',    '~> 0.4.0', require: 'rack/cors'
 
 # Pagination

Gemfile.lock

@@ -316,8 +316,7 @@ GEM
       rack-accept
       rack-mount
       virtus (>= 1.0.0)
-    grape-entity (0.4.8)
-      activesupport
+    grape-entity (0.5.2)
       multi_json (>= 1.3.2)
     haml (4.0.7)
       tilt
@@ -869,7 +868,7 @@ DEPENDENCIES
   gollum-rugged_adapter (~> 0.4.2)
   gon (~> 6.1.0)
   grape (~> 0.15.0)
-  grape-entity (~> 0.4.2)
+  grape-entity (~> 0.5.2)
   haml_lint (~> 0.18.2)
   hamlit (~> 2.6.1)
   health_check (~> 2.2.0)