backend(deps): bump aiohttp

Bumps the pip group with 1 update in the /backend directory: [aiohttp](https://github.com/aio-libs/aiohttp).


Updates `aiohttp` from 3.14.1 to 3.14.3
- [Changelog](https://github.com/aio-libs/aiohttp/blob/master/CHANGES.rst)
- [Commits](aio-libs/aiohttp@v3.14.1...v3.14.3)

---
updated-dependencies:
- dependency-name: aiohttp
  dependency-version: 3.14.3
  dependency-type: direct:production
...

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

Author: dependabot[bot]

backend/requirements.txt

@@ -8,7 +8,7 @@ aiofiles==25.1.0
 python-multipart==0.0.32
 websockets==16.0
 PyYAML==6.0.3
-aiohttp==3.14.1
+aiohttp==3.14.3
 bcrypt==5.0.0
 python-jose[cryptography]==3.5.0
 alembic==1.18.4