Release v0.23.1

Upgrade/jdk 21 compatibility (#88)

* Replacing URL with URI

* Clean up deleted files and add untracked content

* Upgrade Java version from 11 to 21

- Updated maven.compiler.source and maven.compiler.target in root pom.xml
- Updated compiler configuration in simple-cache module
- Prepared project for JDK 21 compatibility
- Requires JDK 21 runtime for compilation

* Modernize CI and bump to 0.23.0-SNAPSHOT

- Replace outdated CI workflows with modern GitHub Actions
- Update to JDK 21/22 matrix builds with latest actions
- Add automated release workflow on PR merge
- Bump version to 0.23.0-SNAPSHOT across all modules

* Fix Maven plugin versions and JDK compatibility

- Update maven-compiler-plugin to 3.13.0 for JDK 19+ support
- Update maven-surefire-plugin to 3.3.1
- Set JDK target to 19 for compatibility with current environment
- Add JDK 19 to CI matrix testing
- Remove redundant compiler config from simple-cache module