Fix exception when trying to unlink minarca on Windows

On Windows, when trying to unlink minarca, we get this error.

2021-09-03 11:10:42,590 [4660][ERROR][MainThread  ] fatal error
Traceback (most recent call last):
  File "minarca_client\ui\widgets.py", line 194, in open
  File "minarca_client\ui\widgets.py", line 226, in pump_events
  File "minarca_client\ui\home.py", line 292, in _handle_unlink
  File "minarca_client\core\__init__.py", line 514, in unlink
  File "minarca_client\core\compat.py", line 371, in delete
  File "<COMObject GetFolder>", line 3, in DeleteTask
pywintypes.com_error: (-2147352567, 'Exception occurred.', (0, None, None, None, 0, -2147024891), None)

1. Make sure to unit test this error.
2. Get it fixed.