asciidoctor-epub3.gemspec in asciidoctor-epub3-1.5.0.alpha.10 vs asciidoctor-epub3.gemspec in asciidoctor-epub3-1.5.0.alpha.11

@@ -34,10 +34,8 @@
   s.add_development_dependency 'rake', '~> 12.3.0'
   s.add_development_dependency 'rspec', '~> 3.9.0'
   s.add_development_dependency 'rubocop', '~> 0.78.0'
   s.add_development_dependency 'rubocop-rspec', '~> 1.37.0'
 
-  s.add_runtime_dependency 'asciidoctor', '>= 1.5.0', '< 3.0.0'
-  s.add_runtime_dependency 'concurrent-ruby', '~> 1.1.0'
+  s.add_runtime_dependency 'asciidoctor', '>= 1.5.3', '< 3.0.0'
   s.add_runtime_dependency 'gepub', '~> 1.0.0'
-  s.add_runtime_dependency 'thread_safe', '~> 0.3.0'
 end