use nixpkgs direnv module

modules/devtools.nix

@@ -19,7 +19,6 @@
       gef
       gdb
       binwalk
-      direnv
       sops
       nil
       nix-index
@@ -44,23 +43,5 @@
   };
   users.users."0xa".extraGroups = [ "wireshark" ];
 
-  ## direnv
-  programs.bash.interactiveShellInit = ''
-    eval "$(direnv hook bash)"
-  '';
-  programs.zsh.interactiveShellInit = ''
-    eval "$(direnv hook zsh)"
-  '';
-  programs.fish.interactiveShellInit = ''
-    direnv hook fish | source
-  '';
-
-  # nix options for derivations to persist garbage collection
-  nix.extraOptions = ''
-    keep-outputs = true
-    keep-derivations = true
-  '';
-  environment.pathsToLink = [
-    "/share/nix-direnv"
-  ];
+  programs.direnv.enable = true;
 }