fix: update newspack-scripts to v5.5.1

[laurelfulford]

All Submissions:

• [x] Have you followed the Newspack Contributing guideline?
• [x] Does your code follow the WordPress' coding standards and VIP Go 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:

This PR bumps the newspack-scripts to 5.5.1, which fixes an issue with generating alpha releases.

How to test the changes in this Pull Request:

1. Confirm that npm run build looks okay!

Other information:

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

[laurelfulford]

🎉

[matticbot]

:tada: This PR is included in version 2.34.0-alpha.1 :tada:

The release is available on GitHub release

Your semantic-release bot :package::rocket:

[matticbot]

:tada: This PR is included in version 2.34.0 :tada:

The release is available on GitHub release

Your semantic-release bot :package::rocket: