CUDA: Add support for cuda_std_20 for nvcc 12.0+
CUDA 12.0 was just released, so update CMake to know that nvcc
now supports -std=c++20.
Backport: release
Topic-rename: cuda-nvcc-cuda20
Edited by Brad King
CUDA 12.0 was just released, so update CMake to know that nvcc
now supports -std=c++20.
Backport: release
Topic-rename: cuda-nvcc-cuda20