Update time crate to >=0.2.23

[tbraun96]

Rust security advisory RUSTSEC-2020-0071 while running cargo deny check advisories is flagged for this crate due to using the old time dependency (due to potential SEGFAULT). The recommendation is to upgrade to time>=0.2.23

[djc]

There have been many issues about this already. The current main branch does not actually use any of the vulnerable code in time 0.1.

[aeshirey]

Despite this issue being closed and also about the vulnerability (which, as you say, doesn't affect chrono), I notice that the current version of time used by this crate lacks features such as certain const functions. It would be nice to be able to create a chrono::Duration in a const context.

[djc]

I'd be open to having more const functions if those would be helpful, though we are somewhat restricted by the current minimum supported Rust version. See also discussion in #638.