Bump jinja2 from 2.10 to 2.11.3

Bumps [jinja2](https://github.com/pallets/jinja) from 2.10 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@2.10...2.11.3)

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

Author: dependabot[bot]

requirements.txt

@@ -1,7 +1,7 @@
 click==6.7
 Flask==1.0.2
 itsdangerous==0.24
-Jinja2==2.10
+Jinja2==2.11.3
 MarkupSafe==1.1.1
 Werkzeug==0.14.1
 honeycomb-beeline==2.11.4