[3.14] GH-136874: `url2pathname()`: discard query and fragment components (GH-136875) (#136942)

GH-136874: `url2pathname()`: discard query and fragment components (GH-136875)

In `urllib.request.url2pathname()`, ignore any query or fragment components
in the given URL.
(cherry picked from commit 80b2d60a51cfd824d025eb8b3ec500acce5c010c)

Co-authored-by: Barney Gale <barney.gale@gmail.com>