Bump notebook in /Machine Learning/Analytics Jupyter Notebooks

Bumps [notebook](https://github.com/jupyter/jupyterhub) from 6.0.2 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>

Author: dependabot[bot]

Machine Learning/Analytics Jupyter Notebooks/ml-analytics-classification-requirements.txt

@@ -26,7 +26,7 @@ mistune==0.8.4
 more-itertools==8.0.0
 nbconvert==5.6.1
 nbformat==4.4.0
-notebook==6.0.2
+notebook==6.1.5
 pandocfilters==1.4.2
 parso==0.5.1
 pexpect==4.7.0