Intuit OAuth2
It appears that `intuit` no longer supports oauth1 (as of December 2019): https://developer.intuit.com/app/developer/qbo/docs/develop/authentication-and-authorization/oauth-1.0a

And, the domain for the url that grant is using doesn't even exist anymore - oauth.intuit.com is now oauth.platform.intuit.com.

Seems to be a straightforward fix - I'm just working on a PR. I'll submit it as soon as I have a chance to test it with the actual provider!

