[2.7] bpo-36816: Update the self-signed.pythontest.net cert (GH-13192) (GH-13199)

[2.7] bpo-36816: Update the self-signed.pythontest.net cert (GH-13192) (GH-13199)

* [2.7] bpo-36816: Update the self-signed.pythontest.net cert (GH-13192)

We updated the server, our testsuite must match.

https://bugs.python.org/issue36816

✈️ CLE -> DEN ✈️ #pycon2019 #beyonce
(cherry picked from commit 6bd81734de0b73f1431880d6a75fb71bcbc65fa1)

The 2.7 tree also needed a certificate in the capath directory updated.
The filename for that was determined by `openssl x509 -in $cert.pem -subject_hash`.

Authored-by: Gregory P. Smith <greg@krypto.org>