Add conversion support for the jiff datetime library

[rumpelsepp]

The author of ripgrep has started a datetime library called jiff. The author provides a in depth comparison with other datetime libraries here. I figure, jiff might gain popularity quickly and it could be a good improvement for pyo3 to provide an implementation for converting to python datetime objects (as it is available for, e.g., chrono).

[bschoenmaeckers]

Sounds like a great exercise. I maybe take a stab at this next week.

[jessekrubin]

I haven't done the conversions (tho I can add them), BUT I did add jiff struct wrappers to my to my side project recently if you are interested in checking it out https://github.com/jessekrubin/ry/blob/main/crates/ryo3-jiff/src

The project is a set of thin(ish) wrappers around several crates.