Update pygments.rb

Fixes #1774

Gemfile

@@ -32,7 +32,7 @@ gem 'grit_ext',      git: "https://github.com/gitlabhq/grit_ext.git",       ref:
 gem "gitolite", '1.1.0'
 
 # Syntax highlighter
-gem "pygments.rb",  git: "https://github.com/gitlabhq/pygments.rb.git", ref: '4db80c599067e2d5f23c5c243bf85b8ca0368ad4'
+gem "pygments.rb",  git: "https://github.com/gitlabhq/pygments.rb.git", branch: "master"
 
 # Language detection
 gem "github-linguist", "~> 2.3.4" , require: "linguist"

Gemfile.lock

@@ -45,8 +45,8 @@ GIT
 
 GIT
   remote: https://github.com/gitlabhq/pygments.rb.git
-  revision: 4db80c599067e2d5f23c5c243bf85b8ca0368ad4
-  ref: 4db80c599067e2d5f23c5c243bf85b8ca0368ad4
+  revision: db1da0343adf86b49bdc3add04d02d2e80438d38
+  branch: master
   specs:
     pygments.rb (0.3.2)
       posix-spawn (~> 0.3.6)