Re-enable fluview "public health lab" data

[melange396]

Fluview "public health lab" data ingestion was commented out due to a problem (in 5a17eaa):

delphi-epidata/src/acquisition/fluview/fluview_update.py

Lines 547 to 548 in 6cc6536

	# TODO: header row has changed for public health lab data
	# update_from_file_public(args.issue, date, args.file, test_mode=args.test)

delphi-epidata/src/acquisition/fluview/fluview_update.py

Lines 554 to 555 in 6cc6536

	# TODO: header row has changed for public health lab data
	# update_from_file_public(issue, date, filename, test_mode=args.test)

Then apparently fixed by #6.

More context in #1638 (comment):

there is data in the fluview_public table with issue dates between Oct 2018 and Aug 2020. Perhaps the code was un-commented-out by hand on the production system way back then, but then it got overwritten or replaced during the flurry of activity that Delphi had in 2020. ¯\_(ツ)_/¯

We can simply turn it back on, or we could take a little more time and patch the missing data as well.