build(deps): bump flask in /server in the pip group across 1 directory

Bumps the pip group with 1 update in the /server directory: [flask](https://github.com/pallets/flask).


Updates `flask` from 2.2.5 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@2.2.5...3.1.3)

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

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

Author: dependabot[bot]

server/requirements.txt

@@ -1,5 +1,5 @@
 dnspython==2.6.1
-Flask==2.2.5
+Flask==3.1.3
 python-dotenv==0.19.0
 pymongo==4.6.3
 gunicorn==23.0.0