test_loader: Workaround pytest 8.2 regression
pytest 8.2 fails to execute an unittest based test suite if the class containing the tests does not define a runTest method, so dynamically define it in the TestCaseWithTransport class from breezy.
pytest 8.2 fails to execute an unittest based test suite if the class containing the tests does not define a runTest method, so dynamically define it in the TestCaseWithTransport class from breezy.