[3.13] gh-143004: Fix possible use-after-free in collections.Counter.update() (GH-143044) (GH-143167)

This happened when the Counter was mutated when incrementing
the value for an existing key.
(cherry picked from commit 86d904588e8c84c7fccb8faf84b343f03461970d)

Co-authored-by: kaushal trivedi <155625932+Kaushalt2004@users.noreply.github.com>