chore(ci): Fixes New Release Changelog Generation GitHub Actions Step

[timnolte]

All Submissions:

• [x] Have you followed the plugin Contributing guideline?
• [x] Does your code follow the WordPress' coding standards?
• [x] Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

• Changes the fromTag to point specifically to the release branch when generating a new changelog during new release builds.

Other information:

• [x] Have you added an explanation of what your changes do and why you'd like us to include them?
• [x] Have you written new tests for your changes, as applicable?
• [x] Have you successfully run tests with your changes locally?

Changelog entry

Enter a summary of all changes on this Pull Request. This will appear in the changelog if accepted.

• Changes the fromTag to point specifically to the release branch when generating a new changelog during new release builds.