Bump minimum pytest

Author: jaraco

setup.cfg

@@ -31,7 +31,7 @@ exclude =
 [options.extras_require]
 testing =
 	# upstream
-	pytest >= 3.5, !=3.7.3
+	pytest >= 4.6
 	pytest-checkdocs >= 1.2.3
 	pytest-flake8
 	pytest-black >= 0.3.7; python_implementation != "PyPy"