Install Poetry from an action in CI (#16)

.github/workflows/main.yml

@@ -21,9 +21,8 @@ jobs:
       uses: actions/setup-python@v2
       with:
         python-version: ${{ matrix.python-version }}
-    # See https://github.com/python-poetry/poetry/issues/366
-    - name: Install Poetry
-      run: pip install poetry
+    - name: Set up Poetry
+      uses: abatilo/[email protected]
     - name: Check package setup
       run: poetry check
     - name: Install dependencies