Minor but critical tweaks to default options for DetailLine + Vendor objects

[jaredthecoder]

As part of Uncat's participation in Intuit's developer growth program, I discovered a major issue with how taxes for non-US locales and this library interact where b/c of the TaxAmount setting being set to 0 in the detailline.py object, I silently would get incorrect tax calculations for non-US clients (e.g. we have many Canadian and UK clients where this presented an issue).

The other update here is to by default not create vendor's as a W9 entity when creating them. A customer raised this to us and upon checking if QBO creates vendors with that checkbox checked, it does not, but this library does. That commit sets the appropriate field to False based on QBO's default of False.

Thank you for keeping up all the hard work on this @ej2! Since I started Uncat nearly 5 years ago, this library has been in my toolkit since day 0! :)

[jaredthecoder]

I keep getting pylint errors in the test runs (that's the last commit) failing. Maybe you can advise on the issue there as I don't see that step in the actions for the main repository.