Thank you for your interest in the package, but it's gone now. It's not been updated for four years and its stuck in the past on OpenAPI 2.0, with far too much work needed to get it up to OAS 3.1.
Go grab https://www.npmjs.com/package/express-openapi-validator, it's apparerntly quite a simple migration!
Or find another tool on https://openapi.tools.