build: remove entt library

include/entt/stl/bit.hpp

@@ -1,20 +0,0 @@
-#ifndef ENTT_STL_BIT_HPP
-#define ENTT_STL_BIT_HPP
-
-/*! @cond ENTT_INTERNAL */
-#if __has_include(<entt/ext/stl/bit.hpp>)
-#    include <entt/ext/stl/bit.hpp>
-#else
-#    include <bit>
-
-namespace entt::stl {
-
-using std::bit_ceil;
-using std::has_single_bit;
-using std::popcount;
-
-} // namespace entt::stl
-#endif
-/*! @endcond */
-
-#endif