This package does not support Python 3.12. Please test it with Python 3.12 as a matter of urgency as the default will change in early June, as per message on gentoo-dev: https://www.mail-archive.com/gentoo-dev@lists.gentoo.org/msg99104.html. Please check the information provided in the tracker. Ask in #gentoo-python on IRC if need any help.
jack2-9999 had 3.12 since September 2023 (with required fixes) but there hasn't been a release yet. Going to keep waiting but, if still nothing, will just do a snapshot when we're about to switch default (simpler than trying to backport the waf nonsense).