Remove duplicate flake8 config

Author: lordmauve

.flake8

@@ -17,4 +17,7 @@ commands =
     py.test --cov=pgzero --basetemp={envtmpdir}
 
 [flake8]
-builtins = Actor,Rect,ZRect,animate,clock,exit,images,keyboard,keymods,keys,mouse,music,screen,sounds,storage,tone
+max-line-length = 88
+builtins =
+        Actor, Rect, ZRect, animate, clock, exit, images, keyboard, keymods,
+        keys, mouse, music, screen, sounds, storage, tone