That you for posting this question. We will update the runtime and push an update to the github repo that contains the sample code.
The good news is the emails are not at risk of ceasing to deliver because of this issue. The solution creates two lambda functions when deployed: CustomInsightsFunction (Node.js) and SendSecurityHubSummaryEmail (Python). The CustomInsightsFunction (Node.js) is a Lambda function that is a custom resource of the CloudFormation Deployment and only runs when the stack is created, updated, or deleted. Its purpose is to setup the Security Hub Custom Insights that are the data source of the email, not to send the email, and once setup the custom insights do not need modification.
Kavita and I are investigating the easiest way to update the runtime and will post the answer here and in the GitHub repository.
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