Remove unnecessary direnv hook from nushell config

The something already adds this apparently

home-manager/modules/nushell/config.nu

@@ -209,11 +209,7 @@ let-env config = {
 
   hooks: {
     pre_prompt: [{
-      code: "
-        let direnv = (direnv export json | from json)
-        let direnv = if ($direnv | length) == 1 { $direnv } else { {} }
-        $direnv | load-env
-      "
+      null
     }]
     pre_execution: [{
       null  # replace with source code to run before the repl input is run