ci: fix poetry install option

Author: hejops

.github/workflows/ci.yml

@@ -56,8 +56,8 @@ jobs:
       - name: Install poetry
         uses: abatilo/actions-poetry@v2
       - name: Install the project dependencies
-        # this is fine, apparently?
-        run: poetry install --only=dev
+        # with, not only!
+        run: poetry install --with=dev
       - name: Run pytest
         run: |
           sed -i -r "/token/ s|$|${{ secrets.TEST_DISCOGS_TOKEN }}|g; /username/ s|$|${{ secrets.TEST_DISCOGS_USERNAME }}|g" ./dita/config