Merge pull request #11 from github/graphql-ruby-1-5-6

Use valid_isolated_input? in place of valid_input?

lib/graphql/relay/walker/query_builder.rb

@@ -244,7 +244,11 @@ module GraphQL::Relay::Walker
       12.times.map { (SecureRandom.random_number(26) + 97).chr }.join
     end
 
-    if GraphQL::VERSION >= "1.4.0"
+    if GraphQL::VERSION >= "1.5.6"
+      def valid_input?(type, input)
+        type.valid_isolated_input?(input)
+      end
+    elsif GraphQL::VERSION >= "1.4.0"
       def valid_input?(type, input)
         allow_all = GraphQL::Schema::Warden.new(->(_) { false }, schema: schema, context: nil)
         type.valid_input?(input, allow_all)