Fix leak with Vulkan allocator

drivers/vulkan/rendering_device_vulkan.cpp

@@ -7048,6 +7048,7 @@ void RenderingDeviceVulkan::finalize() {
 	for (int i = 0; i < staging_buffer_blocks.size(); i++) {
 		vmaDestroyBuffer(allocator, staging_buffer_blocks[i].buffer, staging_buffer_blocks[i].allocation);
 	}
+	vmaDestroyAllocator(allocator);
 
 	//all these should be clear at this point
 	ERR_FAIL_COND(descriptor_pools.size());