Change ADD to COPY (#81944)
Docker docs says "For other items (files, directories) that do not require ADD’s tar auto-extraction capability, you should always use COPY": https://docs.docker.com/develop/develop-images/dockerfile_best-practices/#add-or-copy
I've found this by running https://github.com/hadolint/hadolint
If this goes well, I'll change other files too.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/81944
Approved by: https://github.com/huydhn
