During tests on swh-indexer
When debugging with @olasd the new tox command
First I had the following error: P328
resolved with https://wiki.postgresql.org/wiki/Apt#Quickstart

then I had ImportError: No module named 'swh.deposit'
because in the configuration file there were tasks that shouldn't be dealt during tests on swh-indexer

Lastly when keeping a worker.yml empty file, I had :
AttributeError: 'NoneType' object has no attribute 'get'

This was only solved when the file wasn't emty:
task_modules: [ ]