Currently, the macOS SDK Xcode version is set to 15.0 in the guix release builds.

My understanding is that it should be harmless to bump. Though, it involves a bit of effort to check for determinism. C.f. #32009

So I wonder if it seems appropriate to bump the SDK to the latest version for the next 31.x release, or if it should wait for the 32.x release?

The main visible benefit would be that lexicographical_compare_three_way will be available. C.f. #33772 (comment), and also cc @l0rinc .