python3-subunit: upgrade 1.4.2 -> 1.4.4

python3-subunit: upgrade 1.4.2 -> 1.4.4

License-Update:
 change License file to COPYING.
 add BSD-3-Clause to LICENSE

Changelog:
===========
* Removed use of deprecated "utc" and "utcfromtimestamp"
  methods of "datetime.datetime".
* Fix an issue with date parsing exception handling
* Add support for Python 3.12

Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>