Bump notebook from 6.5.2 to 6.5.7

Bumps [notebook](https://github.com/jupyter/notebook) from 6.5.2 to 6.5.7.
- [Release notes](https://github.com/jupyter/notebook/releases)
- [Changelog](https://github.com/jupyter/notebook/blob/v6.5.7/CHANGELOG.md)
- [Commits](jupyter/notebook@v6.5.2...v6.5.7)

---
updated-dependencies:
- dependency-name: notebook
  dependency-version: 6.5.7
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]