[Python-Dev] Python 3.7: Require OpenSSL >=1.0.2 / LibreSSL >= 2.5.3

[Christian Heimes]

FYI, master on Travis CI now builds and uses OpenSSL 1.1.0g [1]. I have
created a daily cronjob to populate Travis' cache with OpenSSL builds.
Until the cache is filled, Linux CI will take an extra 5 minute.

Christian

[1] https://github.com/python/cpython/pull/5180