Use Poetry, update Docker image

.gitlab-ci.yml

@@ -14,21 +14,21 @@ stages:
 
 build-openapi-scheme:
   stage: build
-  image: python:3.9-alpine
+  image: python:3.10-alpine
   variables:
     SECRET_KEY: not-a-very-secret-key
     DJANGO_SETTINGS_MODULE: steering.settings
     # steering.settings switches to sqlite if the VIRTUAL_ENV environment
     # variable is present. It’s probably a good idea to refactor this to
     # something more explicit.
-    VIRTUAL_ENV: 1
     OPENAPI_JSON: ./public/api.json
   before_script:
     - apk add gcc musl-dev zlib-dev jpeg-dev libmagic
-    - pip install -r requirements.txt
+    - pip install poetry==1.2.1
+    - poetry install --without dev,test --no-root
   script:
     - mkdir public
-    - python3 -m django spectacular --validate --lang en --format openapi-json --file $OPENAPI_JSON
+    - poetry run python manage.py spectacular --validate --lang en --format openapi-json --file $OPENAPI_JSON
   artifacts:
     paths:
       - $OPENAPI_JSON