Bump flask from 2.2.3 to 2.3.1

Bumps [flask](https://github.com/pallets/flask) from 2.2.3 to 2.3.1.
- [Release notes](https://github.com/pallets/flask/releases)
- [Changelog](https://github.com/pallets/flask/blob/2.3.1/CHANGES.rst)
- [Commits](https://github.com/pallets/flask/compare/2.2.3...2.3.1)

---
updated-dependencies:
- dependency-name: flask
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

requirements.txt

@@ -1,7 +1,7 @@
 certifi==2022.12.7
 babel==2.12.1
 flask-babel==3.1.0
-flask==2.2.3
+flask==2.3.1
 jinja2==3.1.2
 lxml==4.9.2
 pygments==2.15.1