I tried based on Sylvain's answer, but cache did not work. Here is a working version as of February 2025.

steps:
  - uses: actions/checkout@v4
  - name: Install poetry
    run: |
      pipx install poetry==1.8.*
      poetry config virtualenvs.create true --local
      poetry config virtualenvs.in-project true --local
  - uses: actions/setup-python@v5
    with:
      python-version: '3.12'
      cache: 'poetry'
  - run: poetry install
  - run: poetry run pytest