Log Message:
py-traitlets: updated to 5.12.0

5.12.0

Enhancements made

- Pass \*\*kwds in MetaHasDescriptors __new__ and __init__

Maintenance and upkeep improvements

- Adopt sp-repo-review
- Cleanup after remove Python 2 support
- Add more project URLs, trove classifiers

Documentation improvements

- Fix docs version