Bump notebook from 6.3.0 to 6.4.1

Bumps [notebook](https://github.com/jupyter/jupyterhub) from 6.3.0 to 6.4.1.
- [Release notes](https://github.com/jupyter/jupyterhub/releases)
- [Changelog](https://github.com/jupyterhub/jupyterhub/blob/main/RELEASE.md)
- [Commits](https://github.com/jupyter/jupyterhub/commits)

---
updated-dependencies:
- dependency-name: notebook
  dependency-type: indirect
...

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