Update aioresponses requirement from 0.7.3 to 0.7.4 in /backend

Updates the requirements on [aioresponses](https://github.com/pnuckowski/aioresponses) to permit the latest version.
- [Release notes](https://github.com/pnuckowski/aioresponses/releases)
- [Commits](https://github.com/pnuckowski/aioresponses/compare/0.7.3...0.7.4)

---
updated-dependencies:
- dependency-name: aioresponses
  dependency-type: direct:development
...

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

backend/Pipfile

@@ -32,7 +32,7 @@ pylint = "2.15.8"
 pytest = "7.2.0"
 pytest-asyncio = "0.20.3"
 aiohttp = "3.8.3"
-aioresponses = "0.7.3"
+aioresponses = "0.7.4"
 
 [requires]
 python_version = "3.10"