'retries=' should be a param of Client too.

[NewUserHa]

say you need to use all 'proxy', 'http2', 'retries':
Currently, you have to manually set the default tranport via:

client = AsyncClient(transport=AsyncHTTPTransport(http2=True, proxy=httpx.Proxy('proxy url'), retries=3))
client.get...

it's hard to use, and the routed proxies still can't use 'retries'.

Therefore I think the client class should accept 'reties' param and pass it into both _init_transport and _init_proxy_transport.

[zanieb]

Hi! I've proposed this before and begun work on the changes — I'll push the draft for you: #2517