Make schema update automatically

It looks like the schema isn't being updated automatically. It should be.

Looks like the files that need updating are here: https://github.com/cdklabs/cdk-from-cfn/tree/main/src/specification

It is not clear to me how those files are produced from the Uluru source.

Here is a stalled attempt at doing an auto-update: https://github.com/cdklabs/cdk-from-cfn/pull/662