Upgrade from Xcode 11.7 to 12.4

[repi]

Quick test to upgrade to 12.4, before upgrading to 12.5. https://github.com/NVIDIAGameWorks/PhysX/issues/321

Although failed on the alloca warning when building with cmake, which is odd as @XAMPPRocky added specific code to force disable that warning 3 months ago for the cmake path:

        // Currently there's bugs when compiling with the latest clang.
        // See: https://github.com/NVIDIAGameWorks/PhysX/issues/321
        .cxxflag("-Wno-alloca")

We do need to get CI in this repo to use/verify latest Xcode