Would it be possible to deprecate (or at least stop enhancing) the current datetime C API and add a new capsule based one instead?

We're trying to get extension module authors to *stop* relying on C level globals, since it causes problems with:

- memory usage analysis
- interpreter reinitialisation
- module reloading
- subinterpreters

Unfortunately, the current design of the datetime C API *requires* the use of C level global state.