Memory leak in typeobject.c for slots update

[nascheme]

Bug report

Bug description:

This bug was introduced by gh-133177. The assumption was that the number of slots to be updated could not exceed a fixed value. However, with subclasses, that's not true. The update_slot_after_setattr() correctly makes the slot updates in that case but doesn't free the heap allocated chunks, leaking memory.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-155978: Fix leak in update_slot_after_setattr() #155979
• [3.15] gh-155978: Fix leak in update_slot_after_setattr() (GH-155979) #155984