datastore_search truncates timestamps to seconds

[wardi]

CKAN version

master

Describe the bug

timestamps stored in postgres can store microsecond values but datastore_search truncates to seconds

ckan/ckanext/datastore/backend/postgres.py

Line 2078 in ce6f837

fmt = "to_char({0}, 'YYYY-MM-DD\"T\"HH24:MI:SS')"

Steps to reproduce

datastore_create or load data with smaller than 1s precision

Expected behavior

Data stored (at least up to postgres accuracy) should be returned by datastore_search

Additional details

We use a trigger to record created/modified timestamps on rows and not returning full accuracy makes our tests fragile