testing/zig: upgrade to 0.12.0
not rebuilt:
- fbp - discontinued, should be removed? https://git.sr.ht/~mil/fbp
- limkd - no commits for a year, is it still maintained? https://git.sr.ht/~mil/limkd
- linuxwave - https://github.com/orhun/linuxwave/pull/8
- river - vendoring has layers
- waylock
- zls