style(nix): apply style fixes

configs/nixos/hosts/zeus/default.nix

@@ -8,7 +8,10 @@
 # Disk layout is in ./disk.nix.
 # `fileSystems` are derived from it, none declared here.
 {
-  imports = [ ./disk.nix ] ++ lib.optional (builtins.pathExists ./hardware-configuration.nix) ./hardware-configuration.nix;
+  imports = [
+    ./disk.nix
+  ]
+  ++ lib.optional (builtins.pathExists ./hardware-configuration.nix) ./hardware-configuration.nix;
 
   nixpkgs.hostPlatform = "x86_64-linux";