Remove deprecated usage of is_pod/is_pod_v (#88918)
… as equivalent replacements for std::is_pod and std::is_pod_v because they are deprecated in C++20.
When consuming libtorch header files in a project that uses C++20, there are warnings about std::is_pod being deprecated. This patch fixes that issue.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/88918
Approved by: https://github.com/ezyang
