fix GitHub workflow badge URL

[shoito]

Summary

Proposed change:

fix GitHub workflow badge URL.

See https://github.com/badges/shields/issues/8671

Checklist

I've completed the checklist below to ensure I didn't forget anything. This makes reviewing this PR as easy as possible for the maintainers. And it gets this change released as soon as possible.

• [ ] Proposed change helps towards purpose of this project.
• [ ] Documentation is added / updated to describe proposed change.
• [ ] Tests are added / updated to cover proposed change.
• [ ] Changelog has an entry for proposed change (if user-facing fix or feature).