Nontrivial way to do it is dynamically scan the python 3.12 namespace, and add these warnings.

Is there any big downside to do it the boring way, hardcode a list and compare the error to the list?

This information is already maintained via `if sys.version_info >= (...):` conditionals in typeshed stubs. I don't think this is important enough to justify maintaining the same information in a duplicate way.