Replace deprecated GHA ::set-output syntax

[phil9909]

Summary

Use the new way of producing outputs in a github action as the old way is deprecated and will be removed (31st May 2023).

This is needed, because workflows/create-draft-release.yml is listed in .syncignore

occam/.github/.syncignore

Line 2 in 26019f3

workflows/create-draft-release.yml

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

See also: paketo-buildpacks/github-config#604

Use Cases

Keep the pipelines alive.

Checklist

• I have viewed, signed, and submitted the Contributor License Agreement.
• I have linked issue(s) that this PR should close using keywords or the Github UI (See docs)
• I have added an integration test, if necessary.
• I have reviewed the styleguide for guidance on my code quality.
• I'm happy with the commit history on this PR (I have rebased/squashed as needed).