[$] Python 3.12: error messages, perf support, and more

Python 3.12 approaches. While the full feature set of the finalrelease-slated for October 2023-is still not completely known, by nowwe have a good sense for what it will offer. It picks up where Python 3.11 left off, improving error messages and performance. These changes are accompanied by a smattering of smallerchanges, though Linux users will likely make use of one in particular:support for the perf profiler.