tmuxcolors-256: Fix window-status-bell-style.

tmux complains "bad style: fg=colour235,bg=160"

Author: simono

tmuxcolors-256.conf

@@ -31,4 +31,4 @@ set-option -g display-panes-colour colour166 #orange
 set-window-option -g clock-mode-colour colour64 #green
 
 # bell
-set-window-option -g window-status-bell-style fg=colour235,bg=160 #base02, red
+set-window-option -g window-status-bell-style fg=colour235,bg=colour160 #base02, red