remove gancio demo link (502 bad gateway)

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

README.md

@@ -1557,7 +1557,7 @@ A [gallery](https://en.wikipedia.org/wiki/Gallery_Software) is software that hel
 - [Photo Stream](https://github.com/waschinski/photo-stream) - Minimalist self-hosted photo stream. ([Demo](https://floremotion.de/)) `MIT` `Ruby`
 - [Photonix](https://photonix.org/) - A new web-based photo management application with object recognition, location awareness, color analysis and other ML algorithms. ([Demo](https://demo.photonix.org/), [Source Code](https://github.com/photonixapp/photonix)) `AGPL-3.0` `Python`
 - [PhotoPrism](https://photoprism.org) - Personal photo management powered by Go and Google TensorFlow.  Browse, organize, and share your personal photo collection, using the latest technologies to automatically tag and find pictures. ([Demo](https://demo.photoprism.app/library/browse), [Source Code](https://github.com/photoprism/photoprism)) `AGPL-3.0` `Go`
-- [Photoview](https://photoview.github.io/) - A simple and user-friendly Photo Gallery for personal servers. It is made for photographers and aims to provide an easy and fast way to navigate directories, with thousands of high resolution photos. ([Demo](https://photos.qpqp.dk/), [Source Code](https://github.com/photoview/photoview)) `GPL-3.0` `Go`
+- [Photoview](https://photoview.github.io/) - A simple and user-friendly Photo Gallery for personal servers. It is made for photographers and aims to provide an easy and fast way to navigate directories, with thousands of high resolution photos. ([Source Code](https://github.com/photoview/photoview)) `GPL-3.0` `Go`
 - [PiGallery 2](https://bpatrik.github.io/pigallery2/) - A directory-first photo gallery website, with a rich UI, optimised for running on low resource servers. ([Source Code](https://github.com/bpatrik/pigallery2)) `MIT` `Docker/Nodejs`
 - [Piwigo](https://piwigo.org/) - Photo gallery software for the web, built by an active community of users and developers. ([Source Code](https://github.com/Piwigo/Piwigo)) `GPL-2.0` `PHP`
 - [Quru Image Server](https://quruimageserver.com/) - High performance dynamically resizing image server offering directory based access control cropping, rotation, color management and other tools. ([Demo](https://quruimageserver.com), [Source Code](https://github.com/quru/qis)) `AGPL-3.0` `Python`
@@ -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`
@@ -1876,7 +1876,7 @@ _See also: [awesome-sysadmin/Code Review](https://github.com/awesome-foss/awesom
 - [RhodeCode](https://rhodecode.com/) - RhodeCode is an open source platform for software development teams. It unifies and simplifies repository management for Git, Subversion, and Mercurial. ([Source Code](https://code.rhodecode.com/)) `AGPL-3.0` `Python`
 - [SCM Manager](https://www.scm-manager.org/) - The easiest way to share and manage your Git, Mercurial and Subversion repositories over http. ([Source Code](https://github.com/scm-manager/scm-manager)) `BSD-3-Clause` `Java`
 - [Sourcehut](https://sourcehut.org/) - A full web git interface with no javascript. ([Demo](https://sr.ht/), [Source Code](https://git.sr.ht/~sircmpwn/git.sr.ht/tree)) `GPL-2.0` `Go`
-- [Taiga](https://taiga.io/) - Agile Project Management Tool based on the Kanban and Scrum methods. ([Source Code](https://github.com/kaleidos-ventures)) `MPL-2.0` `Docker/Python/Nodejs`
+- [Taiga](https://www.taiga.io/) - Agile Project Management Tool based on the Kanban and Scrum methods. ([Source Code](https://github.com/kaleidos-ventures)) `MPL-2.0` `Docker/Python/Nodejs`
 - [Titra](https://titra.io/) - Time-tracking solution for freelancers and small teams. ([Source Code](https://github.com/kromitgmbh/titra)) `GPL-3.0` `Javascript`
 - [Trac](https://trac.edgewall.org/) - Trac is an enhanced wiki and issue tracking system for software development projects. `BSD-3-Clause` `Python`
 - [Traq](https://traq.io/) - Project management and issue tracking system written in PHP. ([Source Code](https://github.com/nirix/traq)) `GPL-3.0` `PHP/Nodejs`