Update test/ruby/test_module.rb

Co-authored-by: Nobuyoshi Nakada <nobu@ruby-lang.org>

test/ruby/test_module.rb

@@ -526,7 +526,7 @@ class TestModule < Test::Unit::TestCase
         super
       end
     end.new
-    assert_equal(true, m < Enumerable)
+    assert_operator(m, :<, Enumerable)
   end
 
   def test_prepend_self