Upstream repository was moved to a different github organization.

[ItsLiyua]

YaLTeR moved the niri repository to its own organization (https://github.com/niri-wm/niri). If you type in the old link (https://github.com/YaLTeR/niri) you'll be redirected to the new link. I'm not quite sure for how long github keeps the redirect alive but in case it gets removed at some point you should probably update your references to the upstream repository.

[sodiboo]

I believe GitHub keeps the old link alive up until the moment the old link refers to a new repository. You're right, though; I should update the links.