Bump Gradle to v9 (libs)

[slominskir]

This issue tracks global upgrade progress of Gradle to version 9 and Java to JDK21 for libs. It's easiest to upgrade all apps I maintain to the same Gradle and Java version all-at-once so I don't have to toggle tools. Note that JDK21 can continue to compile to Java 11 bytecode as needed.

• jlog v5.2.0
• jmyapi v10.0.0
• gradle-cat v1.2.0
• smoothness weblib v4.13.1 (done in mono / multi-project smoothness along with demo app)

Another consideration is publication of libs to Maven Central has changed: JeffersonLab/java-workflows#3. These libs all need to be updated to accommodate new Maven Central Publication API in tandem with the java-workflow update.