If anyone is experiencing this problem, simply fix your version of httpx, using an exact version pre-0.28 or the qualifier <0.28 until the attached PR is merged.

For example: httpx>=0.26,<0.28 or httpx==0.27.2

If anyone is experiencing this problem, simply fix your version of httpx, using an exact version pre-0.28 or the qualifier <0.28 until the attached PR is merged.

For example: httpx>=0.26,<0.28 or httpx==0.27.2

I think this is a bad solution, as other libraries may require newer version or have another constraint.
Perhaps we can just initialize clients outside and pass to the Transport's constructor:

wsdl_client = httpx.Client(
    verify=sslcontext,
    timeout=HTTP_TIMEOUT,
)
httpx_client = httpx.AsyncClient(verify=sslcontext,
                                 timeout=HTTP_TIMEOUT)
transport = AsyncTransport(client=httpx_client, wsdl_client=wsdl_client)
zclient = ZeepClient(
    wsdl_file, transport=transport,
    service_name=bind_soap_service, port_name=bind_soap_port
)