Fix off by one date errors on CT reports

The utc conversion was causing it to cut off hours at the end of the
day as enddate would end up being a datetime object with 10pm today.
You could also just change what value gets passed in as 'startdate': e.g. https://github.com/dimagi/commcare-hq/blob/master/corehq/apps/reports/commtrack/standard.py#L258-258