add pytest-cov plugin to the requirements

README.md

@@ -104,6 +104,8 @@ features here: [todos.md](docs/todos.md)
 - [PyInstaller](https://pyinstaller.readthedocs.io/en/stable/) - used for
   creating the binary
 - [pytest](https://docs.pytest.org/en/latest/) - used for testing
+- [pytest-cov](https://pytest-cov.readthedocs.io/en/latest/) - used for
+  coverage analysis
 
 ## Contributing
 

requirements.txt

@@ -1,3 +1,4 @@
 pyinstaller
 PyQt5
 pytest
+pytest-cov