ci: Update Poetry version in build workflow

When using 1.1.15 on Python 3.12+ we get an error when building:

ModuleNotFoundError: No module named 'six.moves'

Since we dropped Python 3.6 support, we no longer need to use this old
1.1.15 version anyway, so update to the latest 1.x version. 2.0 should
ok too, but it brings more deprecations due to PEP 621 support.

Author: kadler

.github/workflows/build.yml

@@ -30,7 +30,7 @@ jobs:
         python-version: ${{ matrix.python-version }}
     - name: Install Poetry
       run: |
-        curl -sSL https://install.python-poetry.org | python - -y --version 1.1.15
+        curl -sSL https://install.python-poetry.org | python - -y --version 1.8.5
     - name: Install dependencies
       run: |
         poetry config virtualenvs.create false