getting rid of chrono dependency

[extrawurst]

• [ ] right now gitui depends on chrono directly but the few uses can easily use time directly
• [ ] we use simplelog which uses chrono, which should be easy to migrate to flexi_logger unless simplelog gets rid of the chrono usage: issue
• [ ] syntect (open issue) depends on plist (which has a fix merged) which uses/used chrono

this would fix #950 and #951

[extrawurst]

ok simply switching to time will also not work for us since it currently fixes the soundness issue by just not supporting timezone offsets on unix systems

[stale[bot]]

This issue has been automatically marked as stale because it has not had any activity half a year. It will be closed in 14 days if no further activity occurs. Thank you for your contributions.

[stale[bot]]

This issue has been automatically marked as stale because it has not had any activity half a year. It will be closed in 14 days if no further activity occurs. Thank you for your contributions.