Update pytest-cov requirement from ~=3.0.0 to ~=4.0.0

Updates the requirements on [pytest-cov](https://github.com/pytest-dev/pytest-cov) to permit the latest version.
- [Release notes](https://github.com/pytest-dev/pytest-cov/releases)
- [Changelog](https://github.com/pytest-dev/pytest-cov/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/pytest-cov@v3.0.0...v4.0.0)

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

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

requirements.txt

@@ -110,7 +110,7 @@ PyQt5-sip~=12.11.0
 pyqtgraph~=0.12.4
 pyrsistent~=0.18.1
 pytest~=7.1.3
-pytest-cov~=3.0.0
+pytest-cov~=4.0.0
 pytest-forked~=1.4.0
 pytest-mock~=3.8.2
 pytest-rerunfailures~=10.2