`deskew` command flip tuple length bug

[JoOkuma]

dexp/dexp/cli/dexp_commands/deskew.py

Lines 17 to 25 in 6f05363

	def _flip_callback(ctx: click.Context, opt: click.Option, value: Optional[str]) -> Sequence[str]:
	length = len(ctx.params["input_dataset"].channels())
	if value is None:
	value = (False,) * length
	else:
	value = tuple(bool(s) for s in value.split(","))
	if len(value) != length:
	raise ValueError("-fl --flips must have length equal to number of channels.")
	return value

It should validate with the number of selected channels and not the actual number of channels.