fix: ensure invitation feature is disabled when registrations are not

Signed-off-by: Miguel Nogueira <me@nogueira.codes>

app/Http/Requests/InvitationRequest.php

@@ -17,11 +17,7 @@ class InvitationRequest extends FormRequest
 
     public function authorize(): bool
     {
-        if (Options::getOption('enable_registrations')) {
-            return false;
-        }
-
-        return true;
+        return !Options::getOption('enable_registrations');
     }
 
     protected function failedAuthorization()