.NET 6 Minimal API with proxy

I am creating a minimal API using .NET 6. This API calls another API, and I would like to capture that last call in Fiddler (or Postman).

In old ASP.NET we did like this in the web.config:

<system.net>
    <defaultProxy>
      <proxy bypassonlocal="False" usesystemdefault="True" proxyaddress="http://127.0.0.1:8888" />
    </defaultProxy>
  </system.net>

How do you do that in .NET 6?