Add pyOpenSSL dependency in setup.py

[theoo]

On a fresh ubuntu 20.04 install with python3 (and venv), starting rmview fails due to the missing OpenSSL dependency.

Traceback (most recent call last):
  File "/opt/rmview/.venv/bin/rmview", line 5, in <module>
    from rmview.rmview import rmViewMain
  File "/opt/rmview/.venv/lib/python3.8/site-packages/rmview/rmview.py", line 8, in <module>
    from .screenstream.screenshare import ScreenShareStream
  File "/opt/rmview/.venv/lib/python3.8/site-packages/rmview/screenstream/screenshare.py", line 16, in <module>
    from twisted.internet import protocol, reactor, ssl
  File "/opt/rmview/.venv/lib/python3.8/site-packages/twisted/internet/ssl.py", line 58, in <module>
    from OpenSSL import SSL  # type: ignore[import]
ModuleNotFoundError: No module named 'OpenSSL'

Steps to reproduce the issue:

$ pyton3 -m venv .venv
$ source .venv/bin/activate
$ pip install .
$ rmview

Installing SSL lib with pip install pyOpenSSL will fix the issue.

[bordaigorl]

Good catch! Totally forgot about this one. Although I'd actually patch it by requiring twisted[tls] since `pyOpenSSL is a transitive dependency. I'll push a fix shortly