clean: remove unused zip iterator test

test/zip_iterator_test.cxx

@@ -51,13 +51,6 @@ TEST(ZipIteratorTest, CategoryIsMostRestrictiveOfTypes) {
   }
 }
 
-// TEST(ZipIteratorTest, CannotInvokeOperatorArrow) {
-//  std::vector<int> is{1, 2, 3};
-//  std::vector<std::string> ss{"A", "B", "C"};
-//  auto zit = make_zip_iterator(is.begin(), ss.begin());
-//  StaticAssertTypeEq<decltype(zit.operator->()), void>();
-//}
-
 TEST(ZipIteratorTest, CanCombineParallelObjects) {
   std::vector<int> is{1, 2, 3};
   std::vector<std::string> ss{"A", "B", "C"};