build: remove entt library

include/entt/stl/functional.hpp

@@ -1,55 +0,0 @@
-#ifndef ENTT_STL_FUNCTIONAL_HPP
-#define ENTT_STL_FUNCTIONAL_HPP
-
-/*! @cond ENTT_INTERNAL */
-#if __has_include(<entt/ext/stl/functional.hpp>)
-#    include <entt/ext/stl/functional.hpp>
-#else
-#    include <functional>
-#    include <version>
-#    include "../config/config.h"
-
-namespace entt::stl {
-
-using std::equal_to;
-using std::function;
-using std::hash;
-using std::invoke;
-using std::less;
-
-} // namespace entt::stl
-
-#    ifndef ENTT_FORCE_STL
-#        if defined(__cpp_lib_ranges)
-#            define ENTT_HAS_IDENTITY
-namespace entt::stl {
-
-using std::identity;
-
-} // namespace entt::stl
-#        endif
-#    endif
-
-#    ifndef ENTT_HAS_IDENTITY
-#        include <utility>
-
-namespace entt::stl {
-
-struct identity {
-    using is_transparent = void;
-
-    template<typename Type>
-    [[nodiscard]] constexpr Type &&operator()(Type &&value) const noexcept {
-        return std::forward<Type>(value);
-    }
-};
-
-} // namespace entt::stl
-#    endif
-
-#endif
-/*! @endcond */
-
-#undef ENTT_HAS_IDENTITY
-
-#endif