Update pytest-cov requirement from <7 to <8

Updates the requirements on [pytest-cov](https://github.com/pytest-dev/pytest-cov) to permit the latest version.
- [Changelog](https://github.com/pytest-dev/pytest-cov/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/pytest-cov@v1.0...v7.0.0)

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

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

Author: dependabot[bot]

requirements-dev.txt

@@ -1,6 +1,6 @@
 poethepoet
 pyproject-fmt<3
 pytest<9
-pytest-cov<7
+pytest-cov<8
 ruff<0.15
 validate-pyproject<0.24