Fix parser_to_dataframe.py for pathlib Paths

[sgoldenCS]

The current implementation of the data parser does not allow for a filepaths argument to be a single pathlib Path object as it doesn't get converted to an iterable.

Proposed fix: Instead of checking for a string, we should just check if the input is not a list. If filepaths is not a list, we wrap it with a list (assume only one file wants to be loaded).