Update deps of Scala connect-sigv4 example to latest.

[LeifW]

The old version of aws-sigv4-auth-cassandra-java-driver-plugin stops working somewhere past Java 11 at or before Java 17 (Java 19 is the current version) - something kind of error when the aws auth module reflectively loads some Groovy thing?

The latest version works on Java 19.

Also remove the unecessary System.exit(0) call from the end of the main method, and other things that aren't necessary in Scala syntax (semicolons and {} around a lambda).

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