Downgrade poetry to permit extra option with underscores

Fix #545

.github/workflows/release.yml

@@ -22,7 +22,7 @@ jobs:
           python-version: ${{ env.DEFAULT_PYTHON }}
       - name: Install requirements
         run: |
-          python -m pip install --disable-pip-version-check -U pip twine poetry
+          python -m pip install --disable-pip-version-check -U pip twine poetry "poetry-core<1.3.0"
       - name: Build distributions
         run: |
           poetry build -f wheel