[3.11] gh-115146: Fix typo in pickletools.py documentation (GH-115148) (GH-115156)

(cherry picked from commit 4a7f63869aa61b24a7cc2d33f8a5e5a7fd0d76a4)

Co-authored-by: Justin Applegate <70449145+Legoclones@users.noreply.github.com>