Feature request: Log failed results on higher level

[walles]

Could you log failed validations on warning level, and keep non-failed validations at debug?

If you have lots of successes and only a few failures this would make the output a lot easier to read.

https://github.com/EXXETA/openapi-cop/blob/fbc58eb731178268c090bf474cee12d9c5e263a1/src/app.ts#L157-L160