Replace riot.im with matrix.to

contribute.md

@@ -12,7 +12,7 @@ Funkwhale is a community project run by volunteers. There are many ways to help
 We love hearing your feedback and questions, and this is the most simple yet
 effective thing you can do to help us. Reach us on the following platforms:
 
-- Matrix: [#funkwhale:matrix.org](https://riot.im/app/#/room/#funkwhale:matrix.org)
+- Matrix: [#funkwhale:matrix.org](https://matrix.to/#/#funkwhale:matrix.org)
 - Mastodon (official account): [@funkwhale@mastodon.eliotberriot.com](https://mastodon.eliotberriot.com/@funkwhale)
 - Mastodon (maintainer's account): [@eliotberriot@mastodon.eliotberriot.com](https://mastodon.eliotberriot.com/@eliotberriot)
 - Email: contact@eliotberriot.com