libsecret: use plain update policy

pkgs/development/libraries/libsecret/default.nix

@@ -41,6 +41,8 @@ stdenv.mkDerivation rec {
   passthru = {
     updateScript = gnome3.updateScript {
       packageName = pname;
+      # Does not seem to use the odd-unstable policy: https://gitlab.gnome.org/GNOME/libsecret/issues/30
+      versionPolicy = "none";
     };
   };