Bump pytest-cov from 6.3.0 to 7.0.0 in /demos (#1618)

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]

demos/graphql-demo/requirements-dev.txt

@@ -13,5 +13,5 @@ redis==6.4.0
 mypy==1.17.1
 flake8==7.3.0
 pytest==8.4.2
-pytest-cov==6.3.0
+pytest-cov==7.0.0
 sqlalchemy==2.0.43

demos/moderator/requirements-dev.txt

@@ -15,5 +15,5 @@ mypy==1.17.1
 pytest==8.4.2
 pytest-aiohttp==1.1.0
 pytest-asyncio==0.26.0
-pytest-cov==6.3.0
+pytest-cov==7.0.0
 pytest-sugar==1.1.1