isodoc.gemspec in isodoc-1.6.4 vs isodoc.gemspec in isodoc-1.6.5

@@ -24,11 +24,11 @@
 
   spec.bindir        = "bin"
   spec.require_paths = ["lib"]
   spec.files         = `git ls-files`.split("\n")
   spec.test_files    = `git ls-files -- {spec}/*`.split("\n")
-  spec.required_ruby_version = Gem::Requirement.new(">= 2.4.0")
+  spec.required_ruby_version = Gem::Requirement.new(">= 2.5.0")
 
   spec.add_dependency "asciimath"
   spec.add_dependency "html2doc", "~> 1.1.1"
   spec.add_dependency "htmlentities", "~> 4.3.4"
   spec.add_dependency "liquid", "~> 4"
@@ -48,7 +48,8 @@
   spec.add_development_dependency "rexml"
   spec.add_development_dependency "rspec", "~> 3.6"
   spec.add_development_dependency "rubocop", "~> 1.5.2"
   spec.add_development_dependency "sassc", "~> 2.4.0"
   spec.add_development_dependency "simplecov", "~> 0.15"
+  spec.add_development_dependency "metanorma-iso"
   spec.add_development_dependency "timecop", "~> 0.9"
 end