Or just "Jonathan Swift (paraphrase)"

The construction

  to paraphrase Jonathan Swift, "quote goes here"

is similar, but arguably a bit more readable.

That makes it sound like the purpose of paraphrase is to give you license to misquote someone out of laziness, which it isn't. It's supposed to clarify meaning or, with direct quotes it's more often than not used to adapt a quote to the topic at hand.

I think it does clarify meaning in this case: it translates from 18th century English to contemporary English, while retaining the sense of the original.

Good suggestion, I just edited my original comment.

As an aside, I like how the passive-aggression increases line-by-line in your comment.

I was actually entirely earnest. I never before considered how to attribute a commonly quoted line that's almost a true citation, but isn't.

Apocryphal and incorrectly attributed to make it sound like he never even said something with that sense. The two quotes are more than alike enough in sentiment to attribute the idea to him, if not the exact words.

In which case, "Jonathan Swift once said something like...."