build(deps-dev): bump jupyterlab from 4.5.5 to 4.5.6 in /backend

Bumps [jupyterlab](https://github.com/jupyterlab/jupyterlab) from 4.5.5 to 4.5.6.
- [Release notes](https://github.com/jupyterlab/jupyterlab/releases)
- [Changelog](https://github.com/jupyterlab/jupyterlab/blob/main/RELEASE.md)
- [Commits](https://github.com/jupyterlab/jupyterlab/compare/@jupyterlab/lsp@4.5.5...@jupyterlab/lsp@4.5.6)

---
updated-dependencies:
- dependency-name: jupyterlab
  dependency-version: 4.5.6
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]