Bump jinja2 from 2.8 to 2.11.3 in /django_website

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](pallets/jinja@2.8...2.11.3)

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

Author: dependabot[bot]

django_website/requirements.txt

@@ -9,7 +9,7 @@ django-js-reverse==0.9.1
 djangorestframework==3.11.2
 geojson==2.4.0
 imageio==2.3.0
-Jinja2==2.8
+Jinja2==2.11.3
 MarkupSafe==0.23
 matplotlib==2.0.0
 neo4j==1.7.5