Consider switching chrono to jiff

[zbraniecki]

Jiff is a new Rust crate for time management, aligned with Temporal proposal, and better alignment with the direction of the industry.

[zslayton]

Thanks for opening an issue! At least for the time being, chrono is an implementation detail in ion-rust, so replacing it isn't a priority. Would jiff enable any new functionality, or are you just considering the library's general maintenance?

[zbraniecki]

I'm working on a config/storage system which exposes different file stores (JSON, Postcard, TOML, Yaml etc.).
I'm looking to support Timestamp type and based on my research settled on Jiff.
I started looking into Ion today and would like to consider supporting it, but bringing jiff and chrono into my deps is suboptimal, esp that jiff seems like a better choice for Ion.

Totally understand this is not a prio