added Basic.lean so lake stops complaining

Author: arnavdandu

.github/workflows/blueprint.yml

@@ -4,7 +4,6 @@ on:
   push:
     branches:
       - main # Trigger on pushes to the default branch
-      - blueprint
   workflow_dispatch:        # Allow manual triggering of the workflow from the GitHub Actions interface
 
 # Cancel previous runs if a new commit is pushed to the same PR or branch