[libromdata/tests] Fill in the bColorCount fields in the NT 3.5 Notepad icon.

These fields are present in the original RT_GROUP_ICON resource,
but got lost when extracting to .ico format.

TODO: Update the other icons? NT 3.5 is the only one where it's
actually relevant for icon selection, though.

Author: GerbilSoft

src/libromdata/tests/img/ImageDecoder_data/ICO/notepad-nt35-i386-1.ico.gz

@@ -2,7 +2,7 @@
  * ROM Properties Page shell extension. (librptexture)                     *
  * ICO.cpp: Windows icon and cursor image reader.                          *
  *                                                                         *
- * Copyright (c) 2017-2025 by David Korth.                                 *
+ * Copyright (c) 2017-2026 by David Korth.                                 *
  * SPDX-License-Identifier: GPL-2.0-or-later                               *
  ***************************************************************************/