Bump pytest-cov from 6.3.0 to 7.0.0 in /backend (#2250)

Bumps [pytest-cov](https://github.com/pytest-dev/pytest-cov) from 6.3.0 to 7.0.0.
- [Changelog](https://github.com/pytest-dev/pytest-cov/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/pytest-cov@v6.3.0...v7.0.0)

---
updated-dependencies:
- dependency-name: pytest-cov
  dependency-version: 7.0.0
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

backend/poetry.lock

@@ -55,7 +55,7 @@ ruff = "^0.12.8"
 
 [tool.poetry.group.test.dependencies]
 pytest = "^8.3.4"
-pytest-cov = "^6.0"
+pytest-cov = "^7.0"
 pytest-django = "^4.5"
 pytest-mock = "^3.0"
 pytest-xdist = "^3.0"