Bump jinja2 from 2.10.3 to 2.11.3

Bumps [jinja2](https://github.com/pallets/jinja) from 2.10.3 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/2.10.3...2.11.3)

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

requirements.txt

@@ -7,7 +7,7 @@ Flask-Login==0.4.1
 Flask-WTF==0.14.2
 gunicorn==19.9.0
 itsdangerous==1.1.0
-Jinja2==2.10.3
+Jinja2==2.11.3
 MarkupSafe==1.1.1
 SQLAlchemy==1.3.10
 visitor==0.1.3