delete __init__.py from root

[epogrebnyak]

Does this https://github.com/domokane/FinancePy/blob/master/__init__.py have any purpose? Any imports depend on it? (we need to refactor them if they do)

[domokane]

The tests cases may need it.

[epogrebnyak]

The tests cases may need it.

For pytest one might need package to be installed in editable mode with pip install -e ., poetry can enter the enviroment with poetry run pytest. We have to keep in mind this is a bit of red flag something need init.py in root, although not anything to shoot immediately.