Version bump wikimedia-event-utilities and add support to Flink 1.20
Build against wikimedia-event-utilities v1.4.0, Flink 1.20 and Python 3.10.
Keep track of flink-connector-kafka
version independently of
Flink.
Update flink_instant_of_datetime to match the expected input type of of_epoch_milli. This fixes a regression on the Flink 1.20 update path.
Bug: T374359