Unpin poetry in CI tests

.gitlab-ci.yml

@@ -45,7 +45,6 @@ build:
     - !reference [".debian:base", before_script]
     - !reference [".python:pytest", before_script]
     - *install-redis
-    - pip3 install pip==21.0.1 poetry==1.1.8 poetry-core==1.0.4  # https://github.com/python-poetry/poetry/issues/4523#issuecomment-922827488
     - poetry config virtualenvs.create false
     - poetry install -E test
   needs: []