Just use flake8 instead of hacking

We don't use hacking in Infra. Use flake8 instead.

Change-Id: I04ac08a0c4218398b43e906a6d65f75b3ff104c3
diff --git a/tox.ini b/tox.ini
index 835b4ac..46bd1ce 100644
--- a/tox.ini
+++ b/tox.ini
@@ -18,6 +18,7 @@
 
 [flake8]
 # E125 and H are intentionally ignored
-ignore = E125,H
+# W503 is a mistake in flake8
+ignore = E125,H,W503,W504
 show-source = True
 exclude = .venv,.tox,dist,doc,build,*.egg