A team deploys a Lambda function through CodePipeline. The build stage uses CodeBuild to run 'aws cloudformation package' and produce a packaged template, and the deploy stage uses a CloudFormation action to update the function. The team wants each deployment to publish a new immutable Lambda version and route production traffic to it via an alias, so that CodeDeploy can later manage traffic shifting. However, after each pipeline run, the alias still points to $LATEST behavior and no new versions are created. What is the correct way to ensure a new immutable version is published on every deployment?