Allow a better Unit Tests support on cookiecutter base

worker-{{cookiecutter.slug}}/.gitlab-ci.yml

worker-{{cookiecutter.slug}}/Dockerfile

worker-{{cookiecutter.slug}}/tox.ini

...kiecutter.slug}}/worker_{{cookiecutter.slug}}/__init__.py

...ookiecutter.slug}}/worker_{{cookiecutter.slug}}/worker.py