In version 1.4.3:
* Subunit now has a dependency on an external iso8601
module rather than shipping its own.
so add the missing dependency.
(From OE-Core rev: 14ee3e1240524e08adc1a3327dfb52dee6e64fd2)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>