update GNU social source code link

fixes https://github.com/awesome-selfhosted/awesome-selfhosted/issues/2106

README.md

@@ -423,7 +423,7 @@ _[SIP](https://en.wikipedia.org/wiki/Session_Initiation_Protocol)/[IPBX](https:/
 - [FluxBB](http://fluxbb.org/) - Fast, light, user-friendly forum software for your website. ([Source Code](https://github.com/fluxbb/fluxbb)) `GPL-2.0` `PHP`
 - [Friendica](https://friendi.ca/) - Social Communication Server. ([Source Code](https://github.com/friendica/friendica)) `AGPL-3.0` `PHP`
 - [Glosa](https://github.com/glosa/glosa-server) - Open source commentary system easy to integrate with static pages. You can import from Disqus. `GPL-3.0` `Java`
-- [GNU social](https://gnu.io/social/) - Social communication software for both public and private communications. ([Source Code](https://git.gnu.io/gnu/gnu-social)) `AGPL-3.0` `PHP`
+- [GNU social](https://gnu.io/social/) - Social communication software for both public and private communications. ([Source Code](https://notabug.org/diogo/gnu-social)) `AGPL-3.0` `PHP`
 - [Gosora](https://gosora-project.com/) - Gosora is an ultra-fast and secure forum software written in Go that balances usability with functionality. ([Source Code](https://github.com/Azareal/Gosora)) `GPL-3.0` `Go`
 - [Hubzilla](https://hubzilla.org) - Decentralized identity, privacy, publishing, sharing, cloud storage, and communications/social platform. ([Source Code](https://framagit.org/hubzilla/core)) `MIT` `PHP`
 - [HumHub](https://www.humhub.org/) - Flexible kit for private social networks. ([Source Code](https://github.com/humhub/humhub)) `AGPL-3.0` `PHP`