Update pytest-cov requirement from <6,>=2.12.1 to >=2.12.1,<7 (#5144)

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@v2.12.1...v6.0.0)

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

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

requirements-dev.txt

@@ -1,5 +1,5 @@
 pytest>=6.2.1,<9
-pytest-cov>=2.12.1,<6
+pytest-cov>=2.12.1,<7
 pytest-timeout>=1.4.2,<3
 stubserver>=1.1,<2
 setuptools>=65.5.1,<76