strip trailing spaces [ci skip]

test/ostruct/test_ostruct.rb

@@ -256,7 +256,7 @@ class TC_OpenStruct < Test::Unit::TestCase
     os = c.new(foo: :bar)
     assert_equal(:bar, os.foo)
   end
-  
+
   def test_overridden_public_methods
     os = OpenStruct.new(method: :foo, class: :bar)
     assert_equal(:foo, os.method)