Update versions of Maven dependencies and GitHub Actions

[indyteo]

Changes

This PR updates Maven dependencies and GitHub Actions versions to their latest.

Feature description

First, Maven dependencies are all updated. This includes Maven plugins. Main updates are Jackson 3.2.3, which ships with a fix that was blocking for a small simplifications (see third commit), and JUnit 6, which has no breaking change from JUnit 5 for us.

Then, GitHub Actions are all updated. Thankfully, no breaking change were noticed. Everything should be fine when runners will soon switch to Ubuntu 26.

Finally, a tiny simplification which was blocked by an issue in Jackson is now applied, since that issue was fixed in the meantime.

Technical changes

All Maven dependencies versions are now latest.

All GitHub Actions versions are now latest.

Reason

Staying up-to-date is important, for security purpose and to benefit from new updates/patches.

Self-checks

• The code has unit tests associated
• The code has Javadoc Comments associated
• Complex / Unexpected code is explained / justified with a small comment
• Relevant documentation inside the /docs folder has been updated
• All examples in examples/ work the same (or have been adapted if subject to changes in this PR)
• Git history is clean (each commit accomplish a single task and describe it accordingly)
• The texts have been proofread (documentation, error messages, logs, comments...)