use poetry natively?

.github/workflows/ci.yml

@@ -51,9 +51,8 @@ jobs:
       run: |
         python -m pip install --upgrade pip
         pip install poetry
-        poetry export --with dev > requirements.txt
-        pip install -r requirements.txt
+        poetry install --with dev
     - name: Test with pytest
       run: |
-        pytest --cov=pygam
-        codecov
+        poetry run pytest --cov=pygam
+        poetry run codecov