chore: Add release-utils test

What does this MR do?

Adds new bash unit test for scripts/release-util.sh to avoid release failures like !130 (merged)

See pipelines tab for demonstration

Checklist

• Ensure changes can be built upon without requiring a breaking change, see Building for Extensibility.
• Review and add/update tests for this feature/bug.
• Add an entry to the CHANGELOG if required, with the appropriate version. See Classifying Changes.
• Assign the MR to the appropriate person/people for review.