Bump jinja2 from 2.11.3 to 3.1.3 in /demo-bottle

Bumps [jinja2](https://github.com/pallets/jinja) from 2.11.3 to 3.1.3.
- [Release notes](https://github.com/pallets/jinja/releases)
- [Changelog](https://github.com/pallets/jinja/blob/main/CHANGES.rst)
- [Commits](pallets/jinja@2.11.3...3.1.3)

---
updated-dependencies:
- dependency-name: jinja2
  dependency-type: direct:production
...

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

demo-bottle/requirements.txt

@@ -1,4 +1,4 @@
 bottle==0.12.20
 beaker==1.6.4
 paste==1.7.5.1
-jinja2==2.11.3
+jinja2==3.1.3