s3-react-website CREATE_FAILED The runtime parameter of python3.6 is no longer supported

[bfrancom]

Trying out the s3-react-website which should be a pretty common pattern. Doesn't look like it's been updated in over 2 years and probably why it's failing. This is the error I'm getting below:

4:36:48 PM | CREATE_FAILED        | AWS::Lambda::Function       | CustomCDKBucketDep...CCXXXX
Resource handler returned message: "The runtime parameter of python3.6 is no longer supported for creating or updating AWS Lambda functions. We recommend you use the new runtime (python3.9) while creating or updating functions. (Service: Lambda, Status Code: 400, Request ID: xxx)" (RequestToken: xxx, HandlerErrorCode: InvalidRequest)