datetime parsing does not handle generic ISO-8601 strings

Currently the generated from_dict code calls datetime.fromisoformat():

https://github.com/Fatal1ty/mashumaro/blob/53cd94c34006aff7f8b4eaa29d7b5d7037ee4bfd/mashumaro/serializer/base/metaprogramming.py#L468-L471

fromisoformat is only designed to invert the strings generated by datetime.isoformat():

This does not support parsing arbitrary ISO 8601 strings - it is only intended as the inverse operation of datetime.isoformat(). A more full-featured ISO 8601 parser, dateutil.parser.isoparse is available in the third-party package dateutil.

According to mashumaro’s documentation:

use_datetime: False  # False - load datetime oriented objects from ISO 8601 formatted string, True - keep untouched

I believe it should be within mashumaro’s scope to handle generic ISO-8601 strings

[movermeyer]

As of Python 3.11, datetime.fromisoformat can handle all the important bits of the ISO 8601 spec.

I’ll be backporting its code in https://github.com/movermeyer/backports.datetime_fromisoformat/issues/21, so it’ll be available for earlier versions of Python 3.

FWIW, ciso8601 is still faster than any other parser.

[Bao-gxg]

Perfect. I’ll test it out soon, thank you!