Bump jinja2 from 3.1.2 to 3.1.3 in /examples/docker-flask (#620)

Bumps [jinja2](https://github.com/pallets/jinja) from 3.1.2 to 3.1.3.
- [Release notes](https://github.com/pallets/jinja/releases)
- [Changelog](https://github.com/pallets/jinja/blob/main/CHANGES.rst)
- [Commits](https://github.com/pallets/jinja/compare/3.1.2...3.1.3)

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

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examples/docker-flask/requirements.txt

@@ -4,7 +4,7 @@ blinker==1.6.2
 click==8.1.3
 Flask==2.3.2
 itsdangerous==2.1.2
-Jinja2==3.1.2
+Jinja2==3.1.3
 MarkupSafe==2.1.2
 Pillow==10.0.1
 pycups==2.0.1