CI: Testing of Python modules

The main use of CI will be running automatic tests of our Python modules. Set that up.

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Migrated from T1029 (view on Phabricator)

added Continuous Integration priority:High state:wip labels

marked this issue as related to swh/infra/sysadm-environment#1030 (closed)

marked this issue as related to #1247 (closed)

assigned to @douardda

removed state:wip label

closed