fix: demo extractor updated yara

[seb-acsc]

This PR fixes the demo complex extractor for yara v4.3.0 compatibility and adds a test case so we can pick up the failure in the future.

Fixes #56

[seb-acsc]

unfortunately I can't see why the tests failed - is it related to the use of the unittest module?

[cccs-ml]

The tests failed on Py3.8 and Py3.9. Running locally the tests appear to give non-deterministic results on Py3.8 at least.

-              'decoded_strings': ['Complex', 'Paradise'],
?                                  -----------

+              'decoded_strings': ['Paradise', 'Complex'],
?                                            +++++++++++

Re-Running the tests results in some runs passing and others failing.

[cccs-ml]

ps: not related to the use of unittests or tox.

I get the same results running the tests via tox, and also after converting to purely use pytest

[cccs-rs]

We could convert those into sets in the test files, I believe we do that as a workaround in the AL pytests