fix: add license-expression case to get_license

[mckornfield]

Purpose of This Pull Request

Please check the relevant option by placing an "X" inside the brackets:

• [ ] Documentation update
• [x] Bug fix
• [ ] New feature
• [ ] Other (please explain):

Overview of Changes

Provide a concise overview of the changes made in this pull request

Related Issue

Fixes #121

Reviewer Focus

Should be relatively straight forward, didn't see a great way to add a test without importing another package but I can do so