0.2.5 dependencies and tests

Dependencies are unpinned. Declared as:

    'cryptography >= 41.0.0',
    'pyopenssl >= 21.0.0',
    'pem >= 23.1.0',
    'certifi >= 2018.10.15'

Tests are split to two files, test_local.py and test_remote.p. To run local tests: pytest tests/test_local.py. Also, added tests for gencert to test_local.py.