Fix "Exclude flake8 hacking plugins"

Apparently setting "select" overrides the default "ignore" values.

setup.cfg

@@ -13,7 +13,7 @@ known_standard_library = _dummy_thread,_thread,abc,aifc,argparse,array,ast,async
 known_third_party = defusedxml,passlib,pkg_resources,pytest,vobject
 
 [flake8]
-select = E,W,F
+extend-ignore = H
 
 [coverage:run]
 branch = True