Workaround for mypy 0.800 ignoring setup.cfg

See python/mypy#9940

Author: mgedmin

setup.cfg

@@ -17,6 +17,10 @@ ignore = E241,E501,E261,E126,E127,E128,E302,W503
 # E302: expected 2 blank lines, found 0
 # W503: line break before binary operator
 
+# empty [mypy] section required for mypy 0.800, see
+# https://github.com/python/mypy/issues/9940
+[mypy]
+
 # setuptools has no type hints
 [mypy-setuptools.command.egg_info]
 ignore_missing_imports = true