The `expires_in` attribute of `AuthClient` is never set

https://github.com/intuit/oauth-pythonclient/blob/058eedf8f651a8af207e6f6d4a2ebf05e906f7b7/intuitlib/client.py#L67

This value never appears to be updated anywhere in the project. So no matter when this variable is referenced--it will always be `None`. One would imagine that this would need to be updated at some point, right? Of course, I could be missing something here as well.

Start with intuitlib/client.py around line 67, then search the project for every reference to AuthClient.expires_in and determine where its value should come from. Confirm the intended expiration behavior from the OAuth client flow; done means the attribute is updated consistently or the issue is shown to be invalid with supporting tests or documentation.

Scritto dal modello di indicizzazione a partire dal testo della issue.