Bump certifi from 2022.12.7 to 2024.7.4 in /backend

Bumps [certifi](https://github.com/certifi/python-certifi) from 2022.12.7 to 2024.7.4.
- [Commits](https://github.com/certifi/python-certifi/compare/2022.12.07...2024.07.04)

---
updated-dependencies:
- dependency-name: certifi
  dependency-type: direct:production
...

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

backend/requirements.txt

@@ -1,4 +1,4 @@
-certifi==2022.12.7
+certifi==2024.7.4
 dnspython==2.3.0
 eventlet==0.35.2
 python-engineio==4.3.4