Revert "python37Packages.pyspf: 2.0.12 -> 2.0.13"

This reverts commit e3f9c4d7.
This fixes #72791.
Version 2.0.13 of pyspf introduced a bug where some incoming mails can cause a
crash and be falsely rejected. (https://github.com/sdgathman/pyspf/issues/17)