attr_json.gemspec in attr_json-0.2.0 vs attr_json.gemspec in attr_json-0.3.0

@@ -38,9 +38,11 @@
   end
   spec.bindir        = "exe"
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
 
+  spec.required_ruby_version = '>= 2.4.0'
+
   spec.add_runtime_dependency "activerecord", ">= 5.0.0", "< 5.3"
 
   spec.add_development_dependency "bundler", "~> 1.14"
   spec.add_development_dependency "rake", ">= 10.0"
   spec.add_development_dependency "rspec", "~> 3.5"