chore(infra): update flagsmith defaults workflow (#2735)

Author: matthewelwell

.github/workflows/update-flagsmith-environment.yml

@@ -29,7 +29,7 @@ jobs:
         run: make install
 
       - name: Update defaults
-        run: python manage.py updateflagsmithenvironment
+        run: poetry run python manage.py updateflagsmithenvironment
 
       - name: Create Pull Request
         uses: peter-evans/create-pull-request@v5