You must add a repository secret called PYPI_API_TOKEN on your repo settings, this will be your pypi API Token. Beware not to add it as an environment variable, but as a secret.

The action will be triggered on the publication of a new release

on:
  release:
    types: [published]

Setup python, using any version within the range 3.0 <= x < 4.0 (you can customize to your needs).

- name: Set up Python
      uses: actions/setup-python@v3
      with:
        python-version: '3.x'

Installation of poetry, which will install it and lock the packages versions as specified in the pyproject.toml file under [tool.poetry.dependencies].

- name: Install Poetry
      run: |
        curl -sSL https://install.python-poetry.org | python -
        poetry lock

Dependency installation (not really needed, but it helped me verify if the dependencies were ok).

- name: Install dependencies
      run: |
        poetry install

Package building which will create a dist folder to be sent to pypi.

- name: Build package
      run: poetry build

Finally, the package publication, which will run the PyPi token config on poetry and the publication command.

- name: Publish package
      env:
        PYPI_API_TOKEN: ${{ secrets.PYPI_API_TOKEN }}
      run: |
        poetry config pypi-token.pypi ${PYPI_API_TOKEN}
        poetry publish