build: add EnTT library

include/entt/stl/tuple.hpp

@@ -0,0 +1,28 @@
+#ifndef ENTT_STL_TUPLE_HPP
+#define ENTT_STL_TUPLE_HPP
+
+/*! @cond ENTT_INTERNAL */
+#if __has_include(<entt/ext/stl/tuple.hpp>)
+#    include <entt/ext/stl/tuple.hpp>
+#else
+#    include <tuple>
+
+namespace entt::stl {
+
+using std::apply;
+using std::forward_as_tuple;
+using std::get;
+using std::make_from_tuple;
+using std::make_tuple;
+using std::tuple;
+using std::tuple_cat;
+using std::tuple_element;
+using std::tuple_element_t;
+using std::tuple_size;
+using std::tuple_size_v;
+
+} // namespace entt::stl
+#endif
+/*! @endcond */
+
+#endif