Download source: https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/cfn-helper-scripts-reference.html
Which resolves to: https://s3.amazonaws.com/cloudformation-examples/aws-cfn-bootstrap-py3-latest.tar.gz
Untarring the code gives the directory name aws-cfn-bootstrap-2.0, but that's a terrible repo name - so the 2.0 got removed