Make "used" and "executed" optional in the manifest.tsv used in syncToSynapse()

If "used" and "executed" are not listed in the headers of the manifest.tsv, an unhelpful error (error raised from pandas) is displayed:
ValueError: Must have equal len keys and value when setting with an iterable

This is the manifest file I used:

the function worked fine once I added the "used" and "executed" column headers