setup.cfg: Ignore W503

W503 and W504 are contrary to each other and their current coexistence is due
to a pending rule change. One should be ignored to allow proper linebreaks in
long operator sequences. According to current conventions, W503 should be
disabled for future-proof linebreaking.

Author: Penwy

setup.cfg

@@ -1,3 +1,3 @@
 [pycodestyle]
-ignore = E501, E722
-exclude = __init__, venv, env, .venv, ENV, __pycache__
+ignore = E501, E722, W503
+exclude = __init__, venv, env, .venv, ENV, __pycache__