entities."deletedAt" has different type from other timestamp columns

[matthew-white]

In general, our timestamp columns are of type timestamp(3) with time zone, where 3 is the precision value. However, entities."deletedAt" is timestamp without time zone: it differs on "with time zone" and also looks to have a precision value of 6. It looks like it's the only column like that and that other timestamp columns share the same type:

SELECT table_name, column_name, data_type, datetime_precision
FROM information_schema.columns
WHERE data_type ~ 'timestamp' AND table_schema = 'public';

I can't think of an obvious way that these differences would have user-facing effects. For example, we don't filter on entities."deletedAt", so #459 isn't an issue. However, I think it'd be a good idea to make it the same type as other timestamp columns in case the differences lead to subtle issues.