DateTime<Tz>'s implementation for FromPyObject does not consider Pythons's datetime.fold attribute

[elied]

When extracting an ambiguous time from DateTime<Tz>, PyO3 will raise a ValueError. Snippet from chrono.rs:

let naive_dt = NaiveDateTime::new(py_date_to_naive_date(dt)?, py_time_to_naive_time(dt)?);
naive_dt.and_local_timezone(tz).single().ok_or_else(|| {
    PyValueError::new_err(format!(
        "The datetime {:?} contains an incompatible or ambiguous timezone",
        dt
     ))
})

So if your Python datetime is datetime(2024, 11, 3, 1, 30, 0, tzinfo=ZoneInfo("America/Chicago"), fold=1), PyO3 will raise the ValueError.

However, in PEP 495 (added in Python 3.6), all time and datetime objects contain a fold attribute to disambiguate ambiguous times. So the above example should not be ambiguous.

We should be able to easily handle this by using chrono's LocalResult.Ambiguous enum.