https://github.com/vector-im/riot-desktop/releases/tag/v1.6.1 Also updated the package since `riot-desktop` has been moved to its own repository (`github.com/vector-im/riot-desktop`).
Now that we have yarn2nix-moretea in the tree, we can use that instead of the vendored version that was introduced when yarn2nix was removed previously. Also add an update script.