Use default checkout setting in CI script for unit tests

[naykutguven]

This pull request makes a minor update to the unit test workflow configuration. The change removes the explicit checkout of the pull request head ref, simplifying the workflow setup.

[Copilot]

Pull Request Overview

This PR simplifies the unit test workflow configuration by removing the explicit checkout reference parameter, allowing the workflow to use GitHub Actions' default checkout behavior which automatically checks out the correct commit for the triggering event.

• Removes explicit ref parameter from the checkout action
• Simplifies workflow configuration by relying on default GitHub Actions behavior

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}