Bump jinja2 from 2.9.6 to 2.11.3

Bumps [jinja2](https://github.com/pallets/jinja) from 2.9.6 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/2.9.6...2.11.3)

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

requirements.txt

@@ -8,7 +8,7 @@ Flask==0.12.2
 greenlet==0.4.12
 idna==2.5
 itsdangerous==0.24
-Jinja2==2.9.6
+Jinja2==2.11.3
 MarkupSafe==1.0
 python-engineio==1.7.0
 python-socketio==1.7.6