I had wondered the same thing, and after a bit of poking around I have realized - despite being quite a core crate - it's currently maintained by one person (...unclear if they are from Nebraska but otherwise very much exactly xkcd 2347)
There is some details in quodlibetor's comment here:
Unfortunately time is part of the public API of Chrono. To update to time 0.3 we should add a time03 feature and leave the existing time feature and related code alone. If we do that, though, I would be happy to merge the resulting code.
Quote from the linked Reddit post:
Hey folks! I'm the only person with merge privileges on the chrono crate and as y'all have noticed this has been a pretty bad year for my OSS contributions, which sucks for the community.
I want very much for chrono to be a stable foundation for rust crates to build upon -- time is doing a great job experimenting with calendar APIs. That said I would love to give out merge privileges to any people with OSS maintenance history who are interested in helping maintain Chrono. Maybe having folks helping will reduce the stress and make Chrono fun again.
If that sounds like you please feel free to DM me here or email me (my address is <my username>@gmail.com).