[3.12] Docs: Amend codeobject.co_lines docs; end number is exclusive (GH-113970) (#113987)

The end number should be exclusive, not inclusive.
(cherry picked from commit e68806c7122070078507b370b13bb225f8501ff8)

Co-authored-by: Ned Batchelder <ned@nedbatchelder.com>