This commit adds a new runner image for the Nix environment. The "nix:docker://backslashhh/nix:latest" line has been included in the Forgejo configuration, allowing Gitea to use the latest Nix image in the runner.
This commit updates the runner labels in the forgejo.nix file. It changes the URL links for the runner images and specifies the version of Ubuntu to be used. The new labels reference the runner images from the gitea repository rather than Node.js images.
This commit introduces the configuration for the gitea-actions-runner service in the forgejo.nix file. It also includes adding a new encrypted yaml file for the runner token. The configurations set up instances and labels for different versions of Ubuntu.