Outdated SSL sock unit test

[sauwming]

Describe the bug

Currently our SSL sock unit test is quite obsolete, since it involves tests to SSLv2, 3 and TLS 1.0, 1.1, which have been deprecated.
The choice of cipher tested is also outdated since AES-256-CBC is not supported in TLS 1.3 due to vulnerabilities such as BEAST, Lucky 13.

Steps to reproduce

N/A

PJSIP version

2.15.1

Context

N/A

Log, call stack, etc

N/A

Note

Perhaps completely removing TLS 1.0 & 1.1 (and unsafe ciphers) support is not a good idea for now as perhaps the adaptation of the deprecation is lagging (many still use them). It is just we need to consider to promote TLS 1.2 & 1.3 more (e.g: verify if we support them on all backends, avoid using TLS 1.1/older as the default, unit test involves TLS 1.2/1.3 & safe ciphers more).