build: Run tests on Java 26

[ThomasVitale]

No description provided.

[Copilot]

Pull request overview

Updates the CI build workflow to include Java 26 in the test matrix, keeping docling-java continuously validated against the newest JDK line alongside existing supported versions.

Changes:

• Add Java 26 to the jvm-build-test matrix so each module is built and tested on Java 26.
• Add Java 26 to the prepare-test-reports matrix so aggregated reports/Codecov uploads also run for Java 26.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

📢 Thoughts on this report? Let us know!

[github-actions]

:java_duke: JaCoCo coverage report

Overall Project	47.43%	🔴

There is no coverage information present for the Files changed

[github-actions]

	Tests	Passed ✅	Skipped	Failed
Gradle Test Results (all modules & JDKs)	1360 ran	1360 passed	0 skipped	0 failed

Test	Result
No test annotations available

• View Gradle Test Results (all modules & JDKs)

[github-actions]

HTML test reports are available as workflow artifacts (zipped HTML).

• Download: Artifacts for this run

[edeandrea]

Should we really be building against Java 26? We probably only want to support LTS version...

[docling-java-ops]

🎉 This issue has been resolved in v0.5.3 (Release Notes)

[ThomasVitale]

@edeandrea that would be a good thing to decide and document. Don't we wanna build against LTS versions + the current version of Java to make sure it works? I started a discussion in #531 so we can talk about that.