process windows paths for pathlib fixes #111

[zapplecat]

Fixes #111, mock is used for the py2 instances of tests (which don't seem to be part of the CI...?).

Changes proposed in this pull request:

• Convert all paths from windows operations to strings
• Detect unsupported python versions for pathlib paths and throw RuntimeError

Output from Pytest:

============================= test session starts =============================
platform win32 -- Python 3.9.6, pytest-6.1.2, py-1.10.0, pluggy-0.13.1
rootdir: E:\Projects\oschmod, configfile: setup.cfg
collected 21 items

tests\test_oschmod.py ........                                           [ 38%]
tests\test_oschmod_pathlib.py .............                              [100%]

============================== warnings summary ===============================
..\oschmod_venv\lib\site-packages\_pytest\config\__init__.py:1230
  e:\projects\oschmod_venv\lib\site-packages\_pytest\config\__init__.py:1230: PytestConfigWarning: Unknown config option: mock_use_standalone_module

    self._warn_or_fail_if_strict("Unknown config option: {}\n".format(key))

-- Docs: https://docs.pytest.org/en/stable/warnings.html
======================== 21 passed, 1 warning in 4.21s ========================

[zapplecat]

@YakDriver no rush, but how does this PR look?

[grottohub]

bumping this :)