Update for Unicode 15.1

[SnoopJ]

With the release of Unicode 15.1, it's time for another update to unicodedata2.

Aside from bumping UNIDATA_VERSION, the new CJK Ideograph Extension I needs to be added to the unified CJK ranges, and there's also a bug in makeunicodedata.py based on how it handles character properties. This may also a good opportunity to review the changes from #58, and to add Python 3.12 (scheduled to come out on 2 October 2023) to the library's tox configuration.

I have opened an upstream PR since this involves a bugfix in the CPython tooling, I figure I won't open a PR for unicodedata2 until this is merged to minimize drift from the upstream, but I can say that applying the same changeset to the relevant files in unicodedata2 does work and the test suite passes.

EDIT: the upstream PR has landed, PR forthcoming.