fix on setting the proper completions and sets the shell

modules/fish.nix

@@ -1,12 +1,13 @@
 { config, pkgs, lib, ... }:
-
 let
   fish-rust = pkgs.callPackage ../pkgs/fish-rust { };
 in
 {
-  programs.fish.enable = true;
+  programs.fish = {
+    enable = true;
+    package = fish-rust;
+  };
   environment.systemPackages = with pkgs; [
-    fish-rust
     starship
     fzf
     bat
@@ -14,4 +15,5 @@ in
     fd
     ripgrep
   ];
+  users.users.cobray.shell = lib.mkForce fish-rust;
 }