bst_date is a date field. Comparing dates with datetimes in postgres
gets confusing and dangerous. See this example, where a date evaluates
as older than midnight that same day.
```
notification_api=# select '2019-04-01' >= '2019-04-01 00:00';
?column?
----------
f
(1 row)
```
By only using dates everywhere, we reduce the chance of these bugs
happening
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