Fixes the build.
Changes proposed in this pull request:
- apply all of the isort changes that resulted from the latest version
- pin to the latest version (4.3.15) so this doesn't happen again, unless we bump the version on purpose
Fixes#829
* aiohttp openapi basic auth testing
* let oauth_problem_middleware recognize all OAuth exceptions
* scope problem should return 403
* excepting two classes makes more sense than subclassing hacks