Python 3.14 adds some stuff for ALPN protocols advertised in the SSL/TLS

handshake. These changes were causing test failures for a couple

reasons:

Internal Python code was expecting the SSL context object to implement

  a set_alpn_protocols method and have a post_handshake_auth

  attribute.
The extra ALPN handler was inflating the number of SSL contexts on a

  request by one, causing

This change adds those APIs to our test context, and updates the urlopen

tests to filter out the ALPN context(s).

Ran unit tests.