This extends the existing implementation for detecting
bad file permissions to account for calls to pathlib
module functions in addition to those from the os module.

The pathlib chmod and lchmod functions are really just
wrappers around the os module equivalents. However, since
they are class methods, the pre-existing logic in the
code did not consider the corresponding pathlib function calls.

Note that the filename is not easily parsable in the case of pathlib.

Resolves PyCQA#1042

This strengthens the check to reduce false positives.