How to use AuthenticationMiddleware from py-rattler

[FaustinCarter]

Checklist

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What happened?

I can see from the rust code that there appears to be support for netrc authentication (I CTL-F'd for netrc in the source...), but I can't understand how I'm supposed to tell the AuthenticationMiddleware to use the netrc backend from the Python side since the middleware doesn't appear to accept any params to __init__. An example for how to choose between the various backends for auth (i.e. netrc, basic http, bearer token in the request header, etc) would be extremely helpful.

Additional Context

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