Support Fastapi HTTPConnection as well as Request for middleware

[primal100]

I would like to use the AuthJWTclass in Fastapi Middleware (such as in Starlette AuthenticationMiddleware in order to set request.user). However in middleware a fastapi.HTTPConnection is provided instead of a fastapi.Request. Request is a subclass of HTTPConnection.

The AuthJWT class has instance checks for Request throughout so will fail if a HTTPConnection is provided.

This PR makes two changes.

1. Uses HTTPConnection instead of Request in the AuthJWT class. Request will still work as it is a subclass of HTTPConnection so will pass instance checks.
2. HTTPConnection has no method attribute. So request.method has been changed to request.scopes['method'] which is available for both HTTPConnection and Request.

[sijokun]

As always I saw this only now. Changes sound good, will test them and merge in the next few days.

Thanks for PR!

[sijokun]

Sorry that I forgot about your PR. Can you please add tests with usage in Fastapi Middleware and then I will merge it.