[server] improve TZDatetime support by depending on logilab-database 1.15.0 including https://www.logilab.org/ticket/1485893, we can now keep the tzinfo attribute on datetime objects for TZDatetime attributes, so one knows that this is a tz-aware datetime. To easily make it work with backends that have no tz support, we keep converting tz-aware datetime objects into utc naive datetime objects before sending them to the database.

for table, column in [
        ('transactions', 'tx_time'),
        ('tx_entity_actions', 'tx_uuid'),
        ('tx_relation_actions', 'tx_uuid')]:
    repo.system_source.create_index(session, table, column)

commit()