ci: use GITHUB_OUTPUT to expose outputs

[rlespinasse]

GitHub Actions have depreciated the set-output command to avoid vulnerabilities

See changelog https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/

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Please make sure the below checklist is followed for Pull Requests.

• All continuous integration tests are green
• Tests are added where necessary
• The JDL part is updated if necessary
• jhipster-online is updated if necessary
• Documentation is added/updated where necessary
• Coding Rules & Commit Guidelines as per our CONTRIBUTING.md document are followed

When you are still working on the PR, consider converting it to Draft (below reviewers) and adding skip-ci label, you can still see CI build result at your branch.

[DanielFran]

Note sure why this part is not working
@mshima any clue?

[mshima]

matrix.json file doesn't contain a trailing EOL.

[mshima]

Thanks @rlespinasse