Bump jinja2 from 2.10.1 to 2.11.3 in /requirements

Bumps [jinja2](https://github.com/pallets/jinja) from 2.10.1 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/2.10.1...2.11.3)

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

requirements/build.txt

@@ -2,7 +2,7 @@ Flask-Cache==0.13.1
 Flask-Cors==3.0.6
 Flask-SSLify==0.1.5
 Flask==1.0
-Jinja2==2.10.1
+Jinja2==2.11.3
 Werkzeug==0.15.3
 blinker==1.4
 boto3==1.9.37