Update CI to test on JDK 25 (LTS) and remove JDK 24 (non-LTS).

Changes:
- Replace JDK 24 with JDK 25 in test matrix
- Add --enable-native-access=ALL-UNNAMED flag for JDK 24+ tests
- This ensures native library loading works correctly per JEP 472

The CI now tests on: JDK 8, 11, 17, 21, 25 (all LTS versions plus latest)

Related to #689

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Co-Authored-By: Claude <noreply@anthropic.com>