convert_page fails on windows if page_path contains drive letter

[hdkire]

convert_page fails on windows when called with paths containing drive letter as page_path because it treats the drive letter of a windows path as an url scheme.

Env:

Python 3.7.2
Windows 10

Repro:

import htmlark
htmlark.convert_page('C:\\page.html')

=>

Traceback (most recent call last):
  File "Python37\lib\site-packages\htmlark.py", line 177, in convert_page
    _, page_text = _get_resource(page_path)
  File "Python37\lib\site-packages\htmlark.py", line 77, in _get_resource
    raise ValueError("Not local path or HTTP/HTTPS URL", url_parsed.scheme)
ValueError: ('Not local path or HTTP/HTTPS URL', 'c')