fix postgres duration queries to return expected integer type

[websub-hub] / src / db / postgres / sql / topic-get-content-by-id.sql

-- topic including content
SELECT *,
        extract(epoch FROM lease_seconds_preferred)::integer AS lease_seconds_preferred,
        extract(epoch FROM lease_seconds_min)::integer AS lease_seconds_min,
        extract(epoch FROM lease_seconds_max)::integer AS lease_seconds_max
FROM topic
WHERE id = $(topicId)