Bump jinja2 from 2.10.1 to 2.10.3

Bumps [jinja2](https://github.com/pallets/jinja) from 2.10.1 to 2.10.3.
- [Release notes](https://github.com/pallets/jinja/releases)
- [Changelog](https://github.com/pallets/jinja/blob/master/CHANGES.rst)
- [Commits](pallets/jinja@2.10.1...2.10.3)

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

Author: dependabot-preview[bot]

requirements.txt

@@ -1,7 +1,7 @@
 click==7.0
 Flask==1.1.1
 itsdangerous==1.1.0
-Jinja2==2.10.1
+Jinja2==2.10.3
 MarkupSafe==1.1.1
 virtualenv==16.7.8
 Werkzeug==0.16.0