test: please older compilers (like g++13)

test/entt/core/concepts.cpp

@@ -16,6 +16,6 @@ TEST(Concepts, CVRefUnqualified) {
 TEST(Concepts, AllocatorLike) {
     ASSERT_FALSE(entt::allocator_like<int>);
     ASSERT_TRUE(entt::allocator_like<std::allocator<int>>);
-    ASSERT_TRUE(entt::allocator_like<std::allocator<void>>);
     ASSERT_FALSE(entt::allocator_like<std::shared_ptr<int>>);
+    ASSERT_TRUE(entt::allocator_like<std::allocator<std::allocator<int>>>);
 }