Bump rouge to 3.20

Gemfile

@@ -149,7 +149,7 @@ gem 'wikicloth', '0.8.1'
 gem 'asciidoctor', '~> 2.0.10'
 gem 'asciidoctor-include-ext', '~> 0.3.1', require: false
 gem 'asciidoctor-plantuml', '~> 0.0.12'
-gem 'rouge', '~> 3.19.0'
+gem 'rouge', '~> 3.20.0'
 gem 'truncato', '~> 0.7.11'
 gem 'bootstrap_form', '~> 4.2.0'
 gem 'nokogiri', '~> 1.10.9'

Gemfile.lock

@@ -891,7 +891,7 @@ GEM
     rexml (3.2.4)
     rinku (2.0.0)
     rotp (2.1.2)
-    rouge (3.19.0)
+    rouge (3.20.0)
     rqrcode (0.7.0)
       chunky_png
     rqrcode-rails3 (0.1.7)
@@ -1356,7 +1356,7 @@ DEPENDENCIES
   request_store (~> 1.5)
   responders (~> 3.0)
   retriable (~> 3.1.2)
-  rouge (~> 3.19.0)
+  rouge (~> 3.20.0)
   rqrcode-rails3 (~> 0.1.7)
   rspec-parameterized
   rspec-rails (~> 4.0.0)