Apple has released a fourth set of developer betas for iOS 12.1, tvOS 12.1, and watchOS 5.1, less than a week after the release of the third betas. The release notes on this new beta cycle continue to be sparse, with no notes or known issues, suggesting Apple is likely just continuing to fix bugs and performance issues and polish the Group FaceTime and Dual-SIM Standby (DSDS) features that have been discovered in prior iOS 12.1 betas. Details on what’s…