build(deps): bump flask from 2.0.2 to 2.1.3 in /backend (#1499)

Bumps [flask](https://github.com/pallets/flask) from 2.0.2 to 2.1.3.
- [Release notes](https://github.com/pallets/flask/releases)
- [Changelog](https://github.com/pallets/flask/blob/main/CHANGES.rst)
- [Commits](pallets/flask@2.0.2...2.1.3)

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

Signed-off-by: dependabot[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

backend/requirements.txt

@@ -2,7 +2,7 @@
 connexion==2.10.0
 datadog==0.44.0
 fakeredis==1.7.0
-Flask==2.0.2
+Flask==2.1.3
 Flask-Cors==3.0.10
 flask-talisman==0.8.1
 google-cloud-storage==2.1.0