y_petri.gemspec in y_petri-2.3.2 vs y_petri.gemspec in y_petri-2.3.3

@@ -22,6 +22,8 @@
   spec.add_development_dependency "rake"
   spec.add_dependency "y_support"
   spec.add_dependency "gnuplot"
   spec.add_dependency "ruby-graphviz"
   spec.add_dependency "distribution"
+  
+  spec.required_ruby_version = '>= 2.0'
 end