ci: bootstrap poetry instead of using installer

        shell: bash

        run: echo ::set-output name=version::$(python -c "import sys; print('-'.join(str(v) for v in sys.version_info))")

      - name: Install poetry

      - name: Bootstrap poetry

        shell: bash

        run: |

          python get-poetry.py -y --preview

          echo "::set-env name=PATH::$HOME/.poetry/bin:$PATH"

          python -m ensurepip

          python -m pip install --upgrade pip

          python -m pip install .

      - name: Configure poetry

        shell: bash

        run: poetry config virtualenvs.in-project true

        run: python -m poetry config virtualenvs.in-project true

      - name: Set up cache

        uses: actions/cache@v2

      - name: Ensure cache is healthy

        if: steps.cache.outputs.cache-hit == 'true'

        shell: bash

        run: poetry run pip --version >/dev/null 2>&1 || rm -rf .venv

        run: python -m poetry run pip --version >/dev/null 2>&1 || rm -rf .venv

      - name: Upgrade pip

        shell: bash

        run: poetry run python -m pip install pip -U

        run: python -m poetry run python -m pip install pip -U

      - name: Install dependencies

        shell: bash

        run: poetry install

        run: python -m poetry install

      - name: Run pytest

        shell: bash

        run: poetry run python -m pytest -v tests

        run: python -m poetry run python -m pytest -v tests