Discovered that one while writting tls-in-tls http/2 tests in #3030

While we can do

with proxy_from_url("...", ca_certs=DEFAULT_CA) as http:
    ...

we cannot

with proxy_from_url("...", cert_data=open(DEFAULT_CA, "rb").read()) as http:
    ...

output unexpected kw key_cert_data for pool conn

I suspect that we missed propagating required kw.

It is an easy fix.

should patch SSL_KEYWORDS = (....) and class PoolKey(typing.NamedTuple):