Update pythonpublish.yml

Added `parsimonious` install step

.github/workflows/pythonpublish.yml

@@ -17,6 +17,8 @@ jobs:
       run: |
         python -m pip install --upgrade pip
         pip install setuptools wheel twine
+    - name: Install parsimonious
+        pip install parsimonious
     - name: Build and publish
       env:
         TWINE_USERNAME: ${{ secrets.PYPI_USERNAME }}