Changed zig to version 0.9.0 for river.

[BurnyLlama]

If using >=zig-0.9.1 portage emerges zig 0.10.xx-xx, which fails to compile river.

It compiles fine using zig-0.9.0 though, so I see no reason why not to use it. :p

[epsilon-0]

Ha, should know better than to trust upstream :P