build(deps): bump aiohttp from 3.11.8 to 3.11.11 in /backend

---
updated-dependencies:
- dependency-name: aiohttp
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

backend/requirements.txt

@@ -11,7 +11,7 @@ python-jose==3.3.0
 passlib[bcrypt]==1.7.4
 
 requests==2.32.3
-aiohttp==3.11.8
+aiohttp==3.11.11
 async-timeout
 aiocache
 aiofiles