build(deps): Bump jinja2 in /zstackbuild/pypi_source

Bumps [jinja2](https://github.com/pallets/jinja) from 2.7.3 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@2.7.3...2.11.3)

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

Author: dependabot[bot]

zstackbuild/pypi_source/requirements.txt

@@ -9,7 +9,7 @@ Flask==0.10.1
 Flask-Script==2.0.5
 importlib==1.0.3
 itsdangerous==0.24
-Jinja2==2.7.3
+Jinja2==2.11.3
 kombu==3.0.35
 librabbitmq==1.6.1
 MarkupSafe==0.23