Fix spec and lint

Author: rmosolgo

lib/graphql/execution/input_values.rb

@@ -207,7 +207,7 @@ def value_from_ast(value_node, type)
         if value_node.nil?
           nil
         elsif value_node.is_a?(GraphQL::Language::Nodes::VariableIdentifier)
-          v = variable_values[value_node.name]
+          variable_values[value_node.name]
         elsif value_node.is_a?(GraphQL::Language::Nodes::NullValue)
           nil
         elsif type.list?

spec/graphql/execution/input_values_spec.rb

@@ -68,6 +68,7 @@ class ExecutionInputValuesTest < Minitest::Test
 
   class DummyRunner
     def add_step(s); end
+    def schema; TEST_SCHEMA; end
   end
 
   def get_input_values(variables_string: "", variables: nil)