remove gancio demo link (502 bad gateway)

- ref. https://github.com/awesome-selfhosted/awesome-selfhosted/issues/2266

README.md

@@ -1587,7 +1587,7 @@ _Related: [Booking and Scheduling](#booking-and-scheduling)_
 - [Feedka](https://github.com/drabkirn/feedka) `⚠` - Open-source web application that can serve as a platform to get authentic, kindful, and constructive feedback from your friends, family, and co-workers. `AGPL-3.0` `Ruby`
 - [Fider](https://fider.io) - Open source alternative to UserVoice for customer feedback. ([Demo](https://demo.fider.io), [Source Code](https://github.com/getfider/fider)) `MIT` `Go`
 - [Framadate](https://framadate.org/abc/) - Online service for planning an appointment or make a decision quickly and easily: Make a poll, Define dates or subjects to choose, Send the poll link to your friends or colleagues, Discuss and make a decision. ([Demo](https://framadate.org/aqg259dth55iuhwm), [Source Code](https://framagit.org/framasoft/framadate?)) `CECILL-B` `PHP`
-- [Gancio](https://gancio.org/) - A shared agenda for local communities. ([Demo](https://demo.gancio.org/), [Source Code](https://framagit.org/les/gancio)) `AGPL-3.0` `Nodejs`
+- [Gancio](https://gancio.org/) - A shared agenda for local communities. ([Source Code](https://framagit.org/les/gancio)) `AGPL-3.0` `Nodejs`
 - [hitobito](https://hitobito.com/en) - A web application to manage complex group hierarchies with members, events and a lot more. ([Demo](https://demo.hitobito.com/en/users/sign_in), [Source Code](https://github.com/hitobito/hitobito)) `AGPL-3.0` `Ruby`
 - [JD Esurvey](https://www.jdsoft.com/jd-esurvey.html) - Open source enterprise survey web application. ([Source Code](https://github.com/JD-Software/JDeSurvey)) `AGPL-3.0` `Java`
 - [LimeSurvey](https://www.limesurvey.org) - Feature-rich Open Source web based polling software. Supports extensive survey logic. ([Demo](https://demo.limesurvey.org), [Source Code](https://github.com/LimeSurvey/LimeSurvey)) `GPL-2.0` `PHP`