Merge pull request #1556 from progit/dependabot/bundler/asciidoctor-epub3-1.5.0.alpha.19

Update asciidoctor-epub3 requirement from 1.5.0.alpha.18 to 1.5.0.alpha.19

Author: ben

Gemfile

@@ -6,7 +6,7 @@ gem 'asciidoctor', '2.0.12'
 gem 'json', '2.4.1'
 gem 'awesome_print', '1.8.0'
 
-gem 'asciidoctor-epub3', '1.5.0.alpha.18'
+gem 'asciidoctor-epub3', '1.5.0.alpha.19'
 gem 'asciidoctor-pdf', '1.5.3'
 
 gem 'coderay', '1.1.3'