Prevent crash when trying to release buffer from already destroyed memory pool

openVulkanoCpp/Vulkan/Resources/ResourceManager.cpp

@@ -98,6 +98,7 @@ namespace OpenVulkano::Vulkan
 	{
 		transferQueue.waitIdle();
 		transferQueue = nullptr;
+		OnShutdown(this); // Notify all custom resources that it's time to die
 		geometries.clear();
 		nodes.clear();
 		textures.clear();