message: Fix indexed color setting regression
  Commit introduced a regression because of a typo in the chunk slice index for the `parse_rgb_color` call.
  This fixes this issue by resetting it to the state it was before the faulty commit.
diff: @@ -771,7 +771,7 @@ impl<'a, H, W> vte::Perform for Performer<'a, H, W>
  if params.len() > 1 && params.len() % 2 != 0 {
  for chunk in params[1..].chunks(2) {
  let index = parse_number(chunk[0]);
  - let color = parse_rgb_color(chunk[0]);
  + let color = parse_rgb_color(chunk[1]);
  if let (Some(i), Some(c)) = (index, color) {
  self.handler.set_color(i as usize, c);
  return;
  