fix: revert required_ruby_version to >=2.4 for 1.10.x

Author: ilikepi

README.md

@@ -17,7 +17,7 @@ https://github.com/omniauth/omniauth-saml
 ## Requirements
 
 * [OmniAuth](http://www.omniauth.org/) 1.3+
-* Ruby 2.4.x+
+* Ruby 2.1.x+
 
 ## Versioning
 

omniauth-saml.gemspec

@@ -11,7 +11,7 @@ Gem::Specification.new do |gem|
   gem.email         = '[email protected]'
   gem.homepage      = 'https://github.com/omniauth/omniauth-saml'
 
-  gem.required_ruby_version = '>= 2.4'
+  gem.required_ruby_version = '>= 2.1'
 
   gem.add_runtime_dependency 'omniauth', '~> 1.3', '>= 1.3.2'
   gem.add_runtime_dependency 'ruby-saml', '~> 1.17'