Update supported JVMs and CircleCI to Java 25

[Macroz]

#3389 updated REMS code enough to make it work on post JVM 19 code. We can now proceed to updating our supported Java versions (in /docs) and update Circle to use later Java images (if available)

• update all mentions of supported Java in /docs
• update CircleCI to use Java 25 or later
• update CHANGELOG.md (not a new feature but good to know)