Adapt Poetry to use PyPI token

• https://python-poetry.org/docs/configuration#pypi-tokenname
• https://python-poetry.org/docs/repositories#configuring-credentials

pypi: 
  stage: package   
  variable: POETRY_PYPI_TOKEN_PYPI
  rules:
    - if: $CI_COMMIT_TAG
      when: manual
  script:
    - poetry publish

• Set POETRY_PYPI_TOKEN_PYPI CI/CD environment variable
• Test it with test tag

Also do it also for pypi_test? Not sure if the auth via token is also required for pypi_test.