Bump jupyterlab from 4.1.5 to 4.2.1

Bumps [jupyterlab](https://github.com/jupyterlab/jupyterlab) from 4.1.5 to 4.2.1.
- [Release notes](https://github.com/jupyterlab/jupyterlab/releases)
- [Changelog](https://github.com/jupyterlab/jupyterlab/blob/@jupyterlab/[email protected]/CHANGELOG.md)
- [Commits](https://github.com/jupyterlab/jupyterlab/compare/@jupyterlab/[email protected]...@jupyterlab/[email protected])

---
updated-dependencies:
- dependency-name: jupyterlab
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>