chore: remove obsolete method

lib/fotos/organizer.rb

@@ -28,12 +28,5 @@ module Fotos
         dest_path
       end
     end
-
-    private
-    def generate_thumbnails
-      @copied_paths.map do |fp|
-        Thumbnail.new(fp).create
-      end
-    end
   end
 end