As expected, Apple has released a third beta of iOS 9 to developers, adding full support for Apple Music debuted last week with the release of iOS 8.4. Featuring a build number of 13A4293f, the third iOS 9 beta also includes a number of under-the-hood improvements from the second beta, focusing on improving the stability and reliability of the new features in the operating system. A new watchOS beta with a build number of 13S5293f has also been posted,…