Support for Xcode 16 #29

What happened?

Hi,

I tried to run dependency-graph on a new project created using Xcode 16, but unfortunately got the following error:
Error: The element PBXFileSystemSynchronizedRootGroup is not supported.

(Looking on internet, other people using tools relying on Xcode's project description (Cocoapods for example) do have the same kind of issue and their workaround is to replace every occurence of "PBXFileSystemSynchronizedRootGroup" with "PBXGroup", and set some object version to 56)

What are the steps to reproduce?

1- Create an Xcode project using Xcode 16
2- run dependency-graph on this new project

What is the expected behavior?

The tool should run taking into account the new kind of object introduced by Xcode 16