Relax pyOpenSSL version requirement

[avtobiff]

Currently setup.py lists the install requirement pyopenssl<18, but it works
with pyOpenSSL==23.0.0.

Please relax the version requirement on pyOpenSSL for installation.

[TimSC]

I had the error "AttributeError: module 'lib' has no attribute 'X509_V_FLAG_CB_ISSUER_CHECK'" which was fixed by installing pyOpenSSL-23.1.1