fix: add old env var for project cache to sync-demos.yml for the time being

Author: 56kyle

.github/workflows/sync-demos.yml

@@ -5,6 +5,7 @@ on:
       - develop
 
 env:
+  COOKIECUTTER_ROBUST_PYTHON_PROJECT_DEMOS_FOLDER: ${{ github.workspace }}
   COOKIECUTTER_ROBUST_PYTHON__DEMOS_CACHE_FOLDER: ${{ github.workspace }}
   COOKIECUTTER_ROBUST_PYTHON__APP_AUTHOR: ${{ github.repository_owner }}
   ROBUST_PYTHON_DEMO__APP_AUTHOR: ${{ github.repository_owner }}