Upgrade demo to 3.19

[lukaseder]

The demo should be upgraded to 3.19:
https://blog.jooq.org/jooq-3-19-0-released-with-duckdb-trino-oracle-23c-support-join-path-improvements-an-official-gradle-plugin-commercial-maven-repositories-policies-udt-paths-trigger-meta-data-hierarchies-and/

Adding examples for a few new features, including:

• Enhance API to provide access to UDT members jOOQ#228
  • Fix and release this first in 3.19.2: Compilation error in JavaGenerator generated code when <pojosAsJavaRecordClasses> is active and a table references a UDT jOOQ#16039
• Add support for to-many path expressions jOOQ#13639
  • Fix and release this first in 3.19.2 (only Scala affected): ScalaGenerator produces duplicate paths for cyclic foreign key relationships jOOQ#16037
• Add org.jooq.Path<R>, a type to model join paths jOOQ#15005
• Add Policy::inherited to specify whether child tables should inherit a parent table's policies jOOQ#15644
  • Fix this: Wrong query generated from inherited Policy with multiple implicit and explicit join paths jOOQ#16065
• Create an official jooq-codegen-gradle plugin jOOQ#12985

Maybe later:

• Add a Records::intoHierarchy Collector to turn Result into tree representations jOOQ#12341