[3.10] gh-123693: Use platform-agnostic semantics when processing zipfile.Path.name. (#123694)

Applies changes from zipp 3.20.1 and jaraco/zippGH-124
(cherry picked from commit 2231286d78d328c2f575e0b05b16fe447d1656d6)
(cherry picked from commit 17b77bb)

Co-authored-by: Jason R. Coombs <jaraco@jaraco.com>