Flink: Update software versions (Java)

CONFLUENT_VERSION=7.7.1
CRATEDB_VERSION=5.9.3
FLINK_VERSION=1.20.0

Author: amotl

framework/flink/kafka-jdbcsink-java/.env

@@ -1,7 +1,7 @@
 # Software component versions.
-CONFLUENT_VERSION=7.6.0
-CRATEDB_VERSION=5.6.1
-FLINK_VERSION=1.18.1
+CONFLUENT_VERSION=7.7.1
+CRATEDB_VERSION=5.9.3
+FLINK_VERSION=1.20.0
 KCAT_VERSION=1.7.1
 
 # Flink service configuration.