Use older poetry

Author: histrio

.github/workflows/python-tests.yml

@@ -24,7 +24,7 @@ jobs:
       - name: Install dependencies
         run: |
           pip install --upgrade pip
-          pip install "poetry==1.4.2"
+          pip install "poetry==1.1.15"
           poetry install
       - name: Do lint
         run: poetry run flake8 .