Update generated code

Author: kitop

samples/client/petstore/ruby/lib/petstore/api_client.rb

@@ -63,7 +63,7 @@ def call_api(http_method, path, opts = {})
                             :message => response.return_message)
         else
           fail ApiError.new(:code => response.code,
-                            :response_headers => response.headers,
+                            :response_headers => response.headers.to_h,
                             :response_body => response.body),
                response.status_message
         end