Apple has released its Gold Master seed of iOS 6 to registered developers. Listed as build 10A403, the GM build is normally the last to be seeded prior to the software’s official launch, expected on September 19, and as such can be used to submit iOS 6 applications to the App Store for review. It is unclear whether the iOS 6 GM seed will be made available as an over-the-air software update, as has been the case with past iOS 5 and iOS 6 beta releases,…