The `ModalVerbs` `Pattern` includes nonsense words

I was starting work on a new linter involving modal verbs and I noticed the logic in `patterns::modal_verbs.rs` looked wrong where it creates negative forms. I made up a quick `Display` method with a dictionary lookup:

That was probably my fault. I remember working on logic like that but don't remember it looking so broken at the time. I promise I wasn't drinking!