Old timestamps in ksqlDB tumbling windows tutorial

Source records for `ratings` in the ksqlDB tumbling windows tutorial (https://kafka-tutorials.confluent.io/create-tumbling-windows/ksql.html) are 2 years old, which can cause issues in the persistent query output. Since ksqlDB 0.11.0, windowed table output topics are now configured as `compact,delete`, so records with old timestamps might be purged quickly.