Remove keyword from pytest.fail call

Author: domdfcoding

tests/test_docstrings.py

@@ -39,4 +39,4 @@ def test_docstrings(module):
 print(indent(stdout.getvalue(), " "))
 
 ifrunner.failures:
-pytest.fail(msg=f"{runner.failures} tests failed")
+pytest.fail(f"{runner.failures} tests failed")