Make sure the poetry version is recent enough in CI

Signed-off-by: Aurélien Bompard <aurelien@bompard.org>

.github/workflows/main.yaml

@@ -45,7 +45,10 @@ jobs:
 
       - name: Install base Python dependencies
         run: |
-          python3 -m pip install --upgrade tox poetry
+          python3 -m pip install --upgrade tox
+          python3 -m pip install --upgrade poetry>=1.5.0
+          poetry --version
+          which poetry
 
       - name: execute tox
         run: tox -- -v