aspell: 0.60.6.1 -> 0.60.8
See http://aspell.net/aspell-0.60.8.txt for release information.
(#71242)
The fix for CVE-2019-20433 may break compatibility for some
applications, hence a version bump instead of adding a patch.
Also: backport of 648678f6e14ab473e4d52cd98d7c97afcc158dc2