Disable experimental installer in site build

Author: thibaudcolas

.github/workflows/ci.yml

@@ -74,9 +74,11 @@ jobs:
  key: ${{ runner.os }}-python-${{ hashFiles('**/pyproject.toml') }}
  restore-keys: |
  ${{ runner.os }}-python-
- - run: |
- poetry config virtualenvs.create false &&
- poetry install
+ # Disabling experimental installer for compatibility with Python 3.10.
+ # See https://github.com/python-poetry/poetry/issues/4210.
+ - run: poetry config experimental.new-installer false
+ - run: poetry config virtualenvs.create false
+ - run: poetry install
  - run: poetry run django-admin runserver --settings=tests.settings.production --pythonpath=. &
  # Docs website build.
  - run: poetry run mkdocs build --strict