build01: switch to zfs_unstable

hosts/build01/default.nix

@@ -1,4 +1,4 @@
-{ inputs, ... }:
+{ inputs, pkgs, ... }:
 {
   imports = [
     inputs.self.nixosModules.cgroups
@@ -7,6 +7,8 @@
     inputs.srvos.nixosModules.hardware-hetzner-online-amd
   ];
 
+  boot.zfs.package = pkgs.zfs_unstable;
+
   nix.settings.max-jobs = 24;
 
   nixpkgs.hostPlatform.gcc.arch = "znver2";