Update connexion[swagger-ui] requirement in /backend

Updates the requirements on [connexion[swagger-ui]](https://github.com/spec-first/connexion) to permit the latest version.
- [Release notes](https://github.com/spec-first/connexion/releases)
- [Commits](spec-first/connexion@2.6.0...3.2.0)

---
updated-dependencies:
- dependency-name: connexion[swagger-ui]
  dependency-type: direct:production
...

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

Author: dependabot[bot]

backend/requirements.txt

@@ -2,7 +2,7 @@ connexion[swagger-ui] >= 2.6.0; python_version>="3.6"
 # 2.3 is the last version that supports python 3.4-3.5
 connexion[swagger-ui] <= 2.3.0; python_version=="3.5" or python_version=="3.4"
 # prevent breaking dependencies from advent of connexion>=3.0
-connexion[swagger-ui] <= 2.14.2; python_version>"3.4"
+connexion[swagger-ui] <= 3.2.0; python_version>"3.4"
 # connexion requires werkzeug but connexion < 2.4.0 does not install werkzeug
 # we must peg werkzeug versions below to fix connexion
 # https://github.com/zalando/connexion/pull/1044