new action: setup-poetry

[davidkhala]

To have better reuse of below steps regularly

name: python tests
on: push
jobs:
  core:
    runs-on: ubuntu-latest
    defaults:
      run:
        working-directory: py
    steps:
      - uses: actions/checkout@main
      - name: Install Poetry
        uses: snok/install-poetry@main
      - name: Install dependencies
        run: poetry install --all-extras
      - run: poetry run pytest
        working-directory: test

[davidkhala]

workspace: https://github.com/davidkhala/setup-poetry