chore: Remove 'poetry install' as it seems to be already done by 'poetry add'

.github/workflows/tests.yml

@@ -36,7 +36,6 @@ jobs:
       - name: "Install icalendar ${{ matrix.icalendar-version }} and other dependencies"
         run: |
           poetry add icalendar~=${{ matrix.icalendar-version }}.0 --no-interaction
-          poetry install --no-interaction --no-root
 
       - name: "Test with pytest"
         run: |