Fix typo in std::optional test

Author: bmerry

tests/test_python_types.cpp

@@ -353,7 +353,7 @@ test_initializer python_types([](py::module &m) {
         return x.value_or(42);
     }, py::arg_v("x", std::nullopt, "None"));
     m.def("test_no_move_assign", [](const opt_no_move_assign &x) {
-        return x ? x.value : 42;
+        return x ? x->value : 42;
     }, py::argv_("x", std::nullopt, "None"));
 #endif