kitty: fix custom tab_bar.py script

For some reason the script was failing to load due to:

Custom draw tab function failed with error: 'kitty.fast_data_types.Color' object cannot be interpreted as an integer

kitty/tab_bar.py

@@ -23,7 +23,7 @@ def draw_tab(
     orig_bg = screen.cursor.bg
 
     def draw_sep(which: str) -> None:
-        screen.cursor.bg = draw_data.default_bg
+        screen.cursor.bg = draw_data.default_bg.rgb
         screen.cursor.fg = orig_bg
         screen.draw(which)
         screen.cursor.bg = orig_bg