Avoid using xcodebuild under linux

[deadash]

I can use xtool to compile Swift to ipa in Linux, and I tested that cargo-swift can also compile well in Linux, just set -p ios --target aarch64-apple-ios.

The only trouble is that it fails when packaging into xcframework, and reports an error

Failed due to the following error:
Failed to create XCFramework due to the following error:
No such file or directory (os error 2)

Of course, this is because there is no xcodebuild in Linux. Maybe first determine whether the file exists or determine the operating system? Then use another method, such as xcframework to package XCFramework?