build(deps): bump connexion from 2.14.2 to 3.1.0 in /backend

Bumps [connexion](https://github.com/spec-first/connexion) from 2.14.2 to 3.1.0.
- [Release notes](https://github.com/spec-first/connexion/releases)
- [Commits](spec-first/connexion@2.14.2...3.1.0)

---
updated-dependencies:
- dependency-name: connexion
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

backend/requirements.txt

@@ -1,5 +1,5 @@
 -e ../tools #egg=code-coverage-tools
-connexion==2.14.2
+connexion==3.1.0
 datadog==0.49.1
 Flask==2.2.3
 Flask-Cors==4.0.1