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

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

Author: dependabot[bot]

dev-requirements.txt

@@ -30,7 +30,7 @@ hypothesis==3.4.0
     # via -r dev-requirements.in
 imagesize==0.7.1
     # via sphinx
-jinja2==2.8
+jinja2==2.11.3
     # via sphinx
 markupsafe==0.23
     # via jinja2