
Add support for tox testing under Debian Bullseye by enabling a python 3.9 gate and tox target for exercising plugin unit tests. Also fix the pylint gate failure. Story: 2009101 Task: 43129 Signed-off-by: Charles Short <charles.short@windriver.com> Change-Id: Iac6eb206724bccb0e6897e1877e77d4e712f71b6