Bump notebook from 5.7.10 to 6.1.5

Bumps [notebook](https://github.com/jupyter/jupyterhub) from 5.7.10 to 6.1.5.
- [Release notes](https://github.com/jupyter/jupyterhub/releases)
- [Changelog](https://github.com/jupyterhub/jupyterhub/blob/master/CHECKLIST-Release.md)
- [Commits](https://github.com/jupyter/jupyterhub/commits)

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

Pipfile

@@ -6,7 +6,7 @@ verify_ssl = true
 [dev-packages]
 civicpy = {editable = true, path = "."}
 jupyter = "~=1.0"
-notebook = "~=5.7"
+notebook = "~=6.1"
 matplotlib = "~=2.0"
 pytest-cov = "~=2.7"
 python-coveralls = "~=2.9"