[3.11] [3.12] gh-109181: Fix refleak in tb_get_lineno() (GH-111948) (#111951)

[3.12] gh-109181: Fix refleak in tb_get_lineno() (GH-111948)

PyFrame_GetCode() returns a strong reference.
(cherry picked from commit 4b0c875d91727440251a8427a80d8515e39d18cd)

Co-authored-by: Victor Stinner <vstinner@python.org>