chore(deps): bump aiohttp from 3.14.1 to 3.14.3 in /backend

Bumps [aiohttp](https://github.com/aio-libs/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: indirect
...

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Author: dependabot[bot]