chore(workflow): add poetry in publish workflow (#7)

We need poetry to publish, so install it.

Author: tmkujala

.github/workflows/publish.yml

@@ -22,6 +22,9 @@ jobs:
         with:
           python-version: '3.9'
 
+      - name: Install Poetry
+        uses: snok/install-poetry@v1
+
       - name: Configure Poetry
         run: |
           poetry config repositories.publish $REPOSITORY_URL