Support for CUDA 12

[ruze00]

CUDA 12 has been out for a while now and most people are using PyTorch with 12.1. This library should be upgraded if it is still being used.

[Chenxuanqi666]

My cuda version is 12.1, and I can run it on this project，but when install dgl，there is a erro：AttributeError: module 'dgl.function' has no attribute 'copy_src'，The solution is to replace the copy_src(src, out) function with copy_u(u, out)