Fix typo in ConfigData tests

Task list

[Y] The PR represents a single logical change. i.e. Cosmetic updates should go in different PRs.
[Y] Added an entry under the Unreleased section of in the CHANGELOG.md as per format.
[Y] Local clean build passes without issue or fail tests (build.ps1 -ResolveDependency).
[ ] Resource documentation added/updated in README.md.
[ ] Resource parameter descriptions added/updated in README.md, schema.mof and comment-based help.
[ ] Comment-based help added/updated.
[ ] Localization strings added/updated in all localization files as appropriate.
[ ] Examples appropriately added/updated.
[ ] Unit tests added/updated. See DSC Resource Testing Guidelines.
[ ] Integration tests added/updated (where possible). See DSC Resource Testing Guidelines.
[ ] New/changed code adheres to DSC Resource Style Guidelines and Best Practices.

This change is