Use yaml.SafeLoader instead of legacy yaml.Loader (#100443)
See https://github.com/yaml/pyyaml/blob/957ae4d495cf8fcb5475c6c2f1bce801096b68a5/lib/yaml/loader.py#L51
Pull Request resolved: https://github.com/pytorch/pytorch/pull/100443
Approved by: https://github.com/Skylion007
