Update Screensy demo link (#3797)

- https://screensy.stef.link : HTTPSConnectionPool(host='screensy.stef.link', port=443): Max retries exceeded with url: / (Caused by NewConnectionError('<urllib3.connection.HTTPSConnection object at 0x7ff3dc265ea0>: Failed to establish a new connection: [Errno 111] Connection refused'))
- ref. https://github.com/awesome-selfhosted/awesome-selfhosted/issues/3558

README.md

@@ -360,7 +360,7 @@ _See also: [Comparison of CalDAV and CardDAV implementations - Wikipedia](https:
 - [RetroShare](https://retroshare.cc) - Secured and decentralized communication system. Offers decentralized chat, forums, messaging, file transfer. ([Source Code](https://github.com/RetroShare/RetroShare)) `GPL-2.0` `C++`
 - [Revolt](https://revolt.chat/) - Revolt is a user-first chat platform built with modern web technologies. ([Source Code](https://github.com/revoltchat/revolt)) `AGPL-3.0` `Rust`
 - [Rocket.Chat](https://rocket.chat/) - Teamchat solution similar to Gitter.im or Slack. ([Source Code](https://github.com/RocketChat/Rocket.Chat)) `MIT` `Nodejs`
-- [Screensy](https://github.com/screensy/screensy) - Simple peer-to-peer screen sharing solution for sharing your screen with WebRTC. ([Demo](https://screensy.stef.link)) `GPL-3.0` `Nodejs`
+- [Screensy](https://github.com/screensy/screensy) - Simple peer-to-peer screen sharing solution for sharing your screen with WebRTC. ([Demo](https://screensy.marijn.it/)) `GPL-3.0` `Nodejs`
 - [Shhh](https://github.com/smallwat3r/shhh) - Keep secrets out of emails or chat logs, share them using secure links with passphrase and expiration dates. `MIT` `Python`
 - [SimpleX Chat](https://github.com/simplex-chat/simplex-chat) - The most private and secure chat and applications platform - now with double ratchet E2E encryption. `AGPL-3.0` `Haskell`
 - [Soketi](https://soketi.app/) - Soketi is a free, open-source Pusher drop-in alternative. ([Source Code](https://github.com/soketi/soketi)) `MIT` `Nodejs`