Merge pull request #1991 from progit/dependabot/bundler/json-2.8.1

Update json requirement from 2.7.6 to 2.8.1

Author: ben

Gemfile

@@ -3,7 +3,7 @@ source 'https://rubygems.org'
 gem 'rake', '13.2.1'
 gem 'asciidoctor', '2.0.22'
 
-gem 'json', '2.7.6'
+gem 'json', '2.8.1'
 gem 'awesome_print', '1.9.2'
 
 gem 'asciidoctor-fb2', '0.7.0'