CBO report: handle error with 'pubDate'

[aih]

The CBO report scraper and loader in load_cbo (now merged to main, and mostly working) often has an error with the pubdate:

-------- ERROR -------- 'pubDate'

This prevents many (especially earlier) CBO reports from being loaded. I believe the error is on this line, currently line 118 of cbo.py:

pub_date = cbo_data['pubDate']

This should probably be changed to a 'get' with a default (e.g. cbo_data.get('pubDate', '')), and then handle the downstream effects of not having a proper pubDate.