Bump flask in /{{cookiecutter.project_slug}}/requirements

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

---
updated-dependencies:
- dependency-name: flask
  dependency-version: 3.1.3
  dependency-type: direct:production
...

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

Author: dependabot[bot]

{{cookiecutter.project_slug}}/requirements/base.txt

@@ -14,7 +14,7 @@ MarkupSafe==3.0.3
 Werkzeug==3.1.6
 
 # Flask
-Flask==3.1.2
+Flask==3.1.3
 blinker==1.9.0
 click==8.3.1
 itsdangerous==2.2.0