backend(deps-dev): bump pytest-asyncio from 1.3.0 to 1.4.0 in /backend (#33)

Bumps [pytest-asyncio](https://github.com/pytest-dev/pytest-asyncio) from 1.3.0 to 1.4.0.
- [Release notes](https://github.com/pytest-dev/pytest-asyncio/releases)
- [Commits](pytest-dev/pytest-asyncio@v1.3.0...v1.4.0)

---
updated-dependencies:
- dependency-name: pytest-asyncio
  dependency-version: 1.4.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

backend/requirements-dev.txt

@@ -1,4 +1,4 @@
 -r requirements.txt
 pytest==9.0.3
-pytest-asyncio==1.3.0
+pytest-asyncio==1.4.0
 httpx==0.28.1