[chore] Update viper from v1.16.0

[tsmethurst]

This is somehow causing build failures, which I think is due to it (somehow?) updating the experimental slices package we rely on in a few areas, i.e. "golang.org/x/exp/slices". As the build error is complaining that the slices sort function signature has changed. This can be fixed by updating the anonymous function signature we're using, and it would also be worth changing all of those files to instead import the standard library slices package "slices".

Though also to keep in mind, as @daenney pointed out in matrix, this version also seems to be causing issues for others too: spf13/viper#1706

Originally posted by @NyaaaWhatsUpDoc in #2441 (comment)