Bump jinja2 from 2.8 to 2.11.3

Bumps [jinja2](https://github.com/pallets/jinja) from 2.8 to 2.11.3.
- [Release notes](https://github.com/pallets/jinja/releases)
- [Changelog](https://github.com/pallets/jinja/blob/master/CHANGES.rst)
- [Commits](https://github.com/pallets/jinja/compare/2.8...2.11.3)

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

requirements.txt

@@ -9,7 +9,7 @@ ipykernel==4.0.3
 ipython==4.0.0
 ipython-genutils==0.1.0
 ipywidgets==4.0.2
-Jinja2==2.8
+Jinja2==2.11.3
 jsonschema==2.5.1
 jupyter==1.0.0
 jupyter-client==4.0.0