Make same change in other script

Author: pamelafox

app/start.sh

@@ -17,7 +17,7 @@ if [ $? -ne 0 ]; then
 fi
 
 echo 'Creating python virtual environment "backend/backend_env"'
-python -m venv backend/backend_env
+python3 -m venv backend/backend_env
 
 echo ""
 echo "Restoring backend python packages"