maintainers/scripts/update.nix: Do not traverse lists

Lists items are not directly accessible like attributes in attrsets are.
This makes it hard to represent their address in `UPDATE_NIX_ATTR_PATH`
environment variable passed to update scripts.

Given that I only introduced list support for `gnome3` attribute set
and we stopped using them there, let’s remove the list support again.
NixOS modules are better place for package collections anyway.

This was meant to go in with NixOS#98304
but got accidentally omitted somehow.

maintainers/scripts/update.nix

@@ -34,7 +34,7 @@ let
 
   /* Recursively find all packages (derivations) in `pkgs` matching `cond` predicate.
 
-    Type: packagesWithPath :: AttrPath → (AttrPath → derivation → bool) → (AttrSet | List) → List<AttrSet{attrPath :: str; package :: derivation; }>
+    Type: packagesWithPath :: AttrPath → (AttrPath → derivation → bool) → AttrSet → List<AttrSet{attrPath :: str; package :: derivation; }>
           AttrPath :: [str]
 
     The packages will be returned as a list of named pairs comprising of:
@@ -60,8 +60,6 @@ let
                 if path == rootPath || evaluatedPathContent.recurseForDerivations or false || evaluatedPathContent.recurseForRelease or false then
                   dedupResults (lib.mapAttrsToList (name: elem: packagesWithPathInner (path ++ [name]) elem) evaluatedPathContent)
                 else []
-              else if lib.isList evaluatedPathContent then
-                dedupResults (lib.imap0 (i: elem: packagesWithPathInner (path ++ [i]) elem) evaluatedPathContent)
               else []
           else [];
     in