Upgrade gitlab-markup to fix render issue with reStructuredText

Gemfile

@@ -133,7 +133,7 @@ gem 'seed-fu', '~> 2.3.7'
 # Markdown and HTML processing
 gem 'html-pipeline', '~> 2.7.1'
 gem 'deckar01-task_list', '2.0.0'
-gem 'gitlab-markup', '~> 1.6.2'
+gem 'gitlab-markup', '~> 1.6.4'
 gem 'redcarpet', '~> 3.4'
 gem 'commonmarker', '~> 0.17'
 gem 'RedCloth', '~> 4.3.2'

Gemfile.lock

@@ -311,7 +311,7 @@ GEM
       diff-lcs (~> 1.1)
       mime-types (>= 1.16)
       posix-spawn (~> 0.3)
-    gitlab-markup (1.6.3)
+    gitlab-markup (1.6.4)
     gitlab-styles (2.3.2)
       rubocop (~> 0.51)
       rubocop-gitlab-security (~> 0.1.0)
@@ -1046,7 +1046,7 @@ DEPENDENCIES
   gitlab-flowdock-git-hook (~> 1.0.1)
   gitlab-gollum-lib (~> 4.2)
   gitlab-gollum-rugged_adapter (~> 0.4.4)
-  gitlab-markup (~> 1.6.2)
+  gitlab-markup (~> 1.6.4)
   gitlab-styles (~> 2.3)
   gitlab_omniauth-ldap (~> 2.0.4)
   gon (~> 6.2)

changelogs/unreleased/upgrade-gitlab-markup.yml

+---
+title: Fix extra blank line at start of rendered reStructuredText code block
+merge_request: 19596
+author:
+type: fixed