Python has deprecated the PROTOCOL_SSLv2 and PROTOCOL_SSLv3 constants since Python 3.6 and the protocols aren't available in modern OpenSSL. We should not support setting these on our third-party SSLContext implementations.

For completion the following is required:

• It should not be possible to enable SSLv2 or SSLv3 in pyOpenSSL (contrib/pyopenssl) or SecureTransport (contrib/securetransport, contrib/_securetransport)
• Add test cases attempting to set SSLv2 and SSLv3 and ensure that the configuration isn't valid. Should test setting via ssl_version, ssl_minimum_version, and ssl_maximum_version.
  • Because the values mentioned above will be removed in future Python versions we should store their old values within the test suite.