filename column inaccessible with pandas backend and parquet

[praateekmahajan]

Describe the bug

When add_filename=True you can't access the column name because I believe it's a reserved name. Changing it to file_name or path will solve it.

Steps/Code to reproduce bug

Please list minimal steps or code snippet for us to be able to reproduce the bug.

A helpful guide on on how to craft a minimal bug report http://matthewrocklin.com/blog/work/2018/02/28/minimal-bug-reports.

Expected behavior

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Environment overview (please complete the following information)

• Environment location: [Bare-metal, Docker, Cloud(specify cloud provider - AWS, Azure, GCP, Collab)]
• Method of NeMo-Curator install: [pip install or from source]. Please specify exact commands you used to install.
• If method of install is [Docker], provide docker pull & docker run commands used

Environment details

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Otherwise, please provide:

• OS version
• Dask version
• Python version

Additional context

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