registry: use is_void_v as needed

src/entt/entity/registry.hpp

@@ -259,7 +259,7 @@ class basic_registry {
                 using storage_type = storage_for_type<Type>;
                 using alloc_type = typename storage_type::allocator_type;
 
-                if constexpr(std::is_same_v<Type, void> && !std::is_constructible_v<alloc_type, allocator_type>) {
+                if constexpr(std::is_void_v<void> && !std::is_constructible_v<alloc_type, allocator_type>) {
                     // std::allocator<void> has no cross constructors (waiting for C++20)
                     cpool = std::allocate_shared<storage_type>(get_allocator(), alloc_type{});
                 } else {