Bump notebook from 6.4.1 to 6.4.12 in /docker-projects/ipython_notebook

Bumps [notebook](http://jupyter.org) from 6.4.1 to 6.4.12.

---
updated-dependencies:
- dependency-name: notebook
  dependency-type: direct:production
...

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

Author: dependabot[bot]

docker-projects/ipython_notebook/requirements.txt

@@ -22,7 +22,7 @@ matplotlib==3.1.1
 mistune==0.8.4
 nbconvert==5.5.0
 nbformat==4.4.0
-notebook==6.4.1
+notebook==6.4.12
 numpy==1.16.4
 pandas==0.24.2
 pandocfilters==1.4.2