RFR: 7904070: Update to use JUnit 5.13.4

[Jaikiran Pai]

On Mon, 1 Sep 2025 08:35:56 GMT, Christian Stein <cstein at openjdk.org> wrote:

> Please review this change updating the JUnit version to [5.13.4](https://docs.junit.org/current/release-notes/index.html#release-notes-5.13.4).

The change looks OK to me, but to avoid confusion, I think we should use the JBS issue title and the PR description to refer to the JUnit platform version (1.13.4) https://docs.junit.org/current/user-guide/#dependency-metadata-junit-platform which is what we are upgrading here.

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Marked as reviewed by jpai (Reviewer).

PR Review: https://git.openjdk.org/jtreg/pull/282#pullrequestreview-3172944137