Sleuth now integrates with GitHub via a GitHub App. GitHub Apps allow organizations finer-grain control over the permissions and repositories that Sleuth has access to. The app has allowed us to remove some of the access scopes we'd required in the past, we now only require Read access for the repositories and Write access for Status and Actions. The app also allows for a higher API rate limit and allows you to connect as an Organization, not as a User.
Switching over to connecting to GitHub via the App is very simple and seamless. In Sleuth just navigate to your Integrations page, disconnect your existing GitHub integration, then reconnect. You'll be prompted to install and approve the GitHub app and away you go!