Display the actual version of Zig used for compilation

[sagehane]

I found it weird that compiling this project using Zig 0.8.0-pre would still state "Hello, Kernel World from Zig 0.7.1!"

Of course, the way it's currently done could be intentional and just a way to indicate that it compiles with the most recent point-release. If that's the case, feel free to reject this PR.

Oh, and is there any reason why this project lacks a license? Does it have to do with how the original Bare Bones also lacked one?