Removing Sit

Sit is no longer maintained, last updated December 2018.  The website is also no longer up.

README.md

@@ -1846,7 +1846,6 @@ _Related: [Task management & To-do lists](#task-management--to-do-lists), [Softw
 - [Request Tracker](https://www.bestpractical.com/rt/) - An enterprise-grade issue tracking system. ([Source Code](https://github.com/bestpractical/rt)) `GPL-2.0` `Perl`
 - [Roundup Issue Tracker](https://www.roundup-tracker.org/) - A simple-to-use and -install issue-tracking system with command-line, web, REST, XML-RPC, and e-mail interfaces. Designed with flexibility in mind - not just another bug tracker. ([Source Code](https://www.roundup-tracker.org/code.html)) `MIT/ZPL-2.0` `Python`
 - [Sentry On-Premise](https://github.com/getsentry/onpremise) - A powerful error tracking platform with wide language support and a robust API. ([Source Code](https://github.com/getsentry/sentry)) `BSD-3-Clause` `Python/Django`
-- [SIT](https://sit.fyi/) - SCM-agnostic, file-based, offline-first, immutable issue tracker. ([Source Code](https://github.com/sit-fyi/sit)) `MIT` `Apache-2.0` `Rust`
 - [Trudesk](https://trudesk.io/) - Trudesk is an open-source help desk/ticketing solution. ([Source Code](https://github.com/polonel/trudesk)) `Apache-2.0` `Nodejs`
 - [Zammad](https://zammad.org/) - Easy to use but powerful open-source support and ticketing system. ([Source Code](https://github.com/zammad/zammad)) `AGPL-3.0` `Ruby`