When you add a new iOS/macOS project on bitrise.io the default Xcode version for the project will be Xcode 8.3 now, instead of the previous Xcode 8.2
Of course you can set another Xcode version right there on the Add New App page (and after the registration on the Settings tab of the app), it’s just the default we changed.
This change does not affect previously registered projects of course, it’s just the default value what changed, on the Add New App page.