Converting old theme format (.blt) to new version (.xml)

Hello, I recently have this good theme from an old version of theme manager .blt format and I would like to use it with the latest version which is now xml. Is there a way to convert it without doing it manually?

Have you tried opening the theme in a version of blender that supports the .blt file, save your blend file, open it in the current blender and save the theme

Yes, it just saves the layout and not the theme colors, etc.