The only place where `OpenSSL` is used is via an indirect dependency
from `urllib3.contrib.pyopenssl`, which itself is only used when
the Python built-in SSL module doesn't support SNI (Server Name Indication).

That module itself is only imported via the vendored `requests` init,
_iff_ `ssl.HAS_SNI` is `False`, or as an optional import in vendored `requests.help`
(which is never imported by code; in the original `requests` library, it's supposed
to be run as a command-line module, but it's unlikely `python -m oci._vendor.requests.help`
is a real use case).

The `urllib3.contrib.pyopenssl` module's docstring says:

> This module was relevant before the standard library ``ssl``
> module supported SNI, but now that we've dropped support for
> Python 2.7 all relevant Python versions support SNI so
> **this module is no longer recommended**.

This is related to oracle#802;
right now there are upper version pins on `pyOpenSSL`, which prevent downstream users
from upgrading to e.g. non-vulnerable versions of that library downstream.

Signed-off-by: Aarni Koskela <akx@iki.fi>