Migrate from JUnit 4 to JUnit 5

Description

Updated pom.xml and the single unit test. Made the test methods package private and removed the "test" prefix in method name, per JUnit 5 best practices.

Related Issue

#125

Motivation and Context

JUnit 4 was been replaced by JUnit 5 approximately 8 years ago.

How Has This Been Tested?

Ran maven verify to prove the tests still pass.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.