tmux: Fix MouseDragEnd1StatusDefault for v3.4

move-window does not support format parsing. Apparently it was a bug
that it did in the past. Fix this by using run-shell - which I hate as a
solution.

.config/tmux/tmux.conf

@@ -86,7 +86,7 @@ bind -n MouseDrag1Status swap-window -d -t=
 # TODO: do nothing on drags that don't start on a window name
 bind -n MouseDragEnd1StatusDefault \
 	if -F "#{e|>|f|0:#{mouse_x},#{e|/|f:#{window_width},2}}" {
-		move-window -t #{last_window_index} -a
+		run-shell "tmux move-window -at #{last_window_index}"
 	} {
 		move-window -t0
 	}