remove unused tox.ini

Author: MKoesters

pyproject.toml

@@ -34,7 +34,6 @@ commands =
     pytest {posargs}
 
 [testenv:coverage]
-deps = -Ur{toxinidir}/requirements_dev.txt
 commands =
     coverage erase
     coverage run --source=ursgal {envbindir}/pytest {posargs}