Don't beep if there is no next snippet cursor

Now the keybinding can be overridden (e.g. using Tab for it as well as
normal behavior), beeping when there is no next cursor is more annoying
than useful.

src/editor.c

@@ -2564,7 +2564,6 @@ gboolean editor_goto_next_snippet_cursor(GeanyEditor *editor)
 	}
 	else
 	{
-		utils_beep();
 		return FALSE;
 	}
 }