(relays|bridges)_published in Pyonionoo should not depend on relays/bridges contained in result
(relays|bridges)_published in Pyonionoo contains the latest timestamp of relays/bridges contained in the result. If there are no bridges/relays, the respective published time is 1900-01-01. If the returned bridges/relays were not offline for a few hours, that time is returned as published time.
I admit that the Onionoo protocol specification was imprecise there by specifying what's currently implemented in Pyonionoo. But the current Onionoo behavior makes more sense for clients. Tweaked the specification.
(relays|bridges)_published fields should contain the timestamps when the last consensus known to Onionoo/Pyonionoo became valid and when the last known bridge network status was published.