change the Gemfile to use new versions of the appropriate tools. Similarly to Rakefile

Author: marrinosnis

Gemfile

@@ -1,21 +1,23 @@
-source 'https://rubygems.org'
+# frozen_string_literal: true
 
-gem 'rake'
-gem 'asciidoctor', '1.5.6.1'
+source "https://rubygems.org"
 
-gem 'json'
-gem 'awesome_print'
+gem 'rake', '13.2.1'
+gem 'asciidoctor', '2.0.23'
 
-gem 'asciidoctor-epub3', :git => 'https://github.com/asciidoctor/asciidoctor-epub3'
-gem 'asciidoctor-pdf', '1.5.0.alpha.16'
-gem 'asciidoctor-pdf-cjk', '~> 0.1.3'
-gem 'asciidoctor-pdf-cjk-kai_gen_gothic', '~> 0.1.1'
+gem 'json', '2.11.3'
+gem 'awesome_print', '1.9.2'
 
-gem 'coderay'
-gem 'pygments.rb'
-gem 'thread_safe'
-gem 'epubcheck-ruby'
-gem 'kindlegen'
+gem 'asciidoctor-fb2', '0.8.0'
+gem 'asciidoctor-epub3', '2.1.3'
+gem 'asciidoctor-pdf', '2.3.19'
+
+gem 'coderay', '1.1.3'
+gem 'pygments.rb', '3.0.0'
+gem 'thread_safe', '0.3.6'
+gem 'epubcheck-ruby', '5.2.1.0'
+gem 'html-proofer', '5.0.10'
+gem 'kindlegen', '3.1.1'
+
+# gem "rails"
 
-gem 'octokit'
-gem 'github_changelog_generator', github: 'Furtif/github-changelog-generator'