Since I8f5338b7eee31f1b8bc3e783d10666e3092a6540 we have not been running pep8 jobs in CI. This change fixes the issues introduced since then, and adds the job back. Unlike the original change, we are not using the openstack-python3-jobs template since it would use py38 on this branch. Change-Id: Ie15019f91b9e7b7f8cf97b628886f6b0beeb24fa (cherry picked from commit610433b11b) (cherry picked from commit022b2be9fc)