Security vulnerability with time: v0.1.43

[appetrosyan]

Hi, we're using ursa in hyperledger iroha, When we ran cargo audit We found

Crate:         time
Version:       0.1.43
Title:         Potential segfault in the time crate
Date:          2020-11-18
ID:            RUSTSEC-2020-0071
URL:           https://rustsec.org/advisories/RUSTSEC-2020-0071
Solution:      Upgrade to >=0.2.23
Dependency tree: 
time 0.1.43

And cargo tree showed time as a direct dependency of ursa.

[hartm]

I think time is only used for performance benchmarking, so this shouldn't be a security vulnerability for Ursa. But it definitely should be updated, so thanks for pointing this out!