Only four days after the public release of iOS 11.3, Apple has already begun testing of iOS 11.4, releasing the first beta to developers yesterday afternoon. The release notes for the initial iOS 11.4 beta list few significant changes, although they note the return of Messages in iCloud — a feature that was promised for iOS 11 last fall and introduced to beta testers in the entire iOS 11.3 beta before being omitted from last week’s final release.…