Update pytest-cov requirement from <4.1,>=3.0 to >=3.0,<4.2

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@v3.0.0...v4.1.0)

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

Signed-off-by: dependabot[bot] <[email protected]>

requirements/testing.txt

@@ -2,5 +2,5 @@
 # --------------------
 
 pillow>=9.4,<10
-pytest-cov>=3.0,<4.1
+pytest-cov>=3.0,<4.2
 validators>=0.19,<0.21