Update flake8 in dev requirements.
Update flake8 in dev requirements.

akatsoulas/remo,flamingspaz/remo,akatsoulas/remo,tsmrachel/remo,mozilla/remo,akatsoulas/remo,flamingspaz/remo,mozilla/remo,flamingspaz/remo,tsmrachel/remo,mozilla/remo,mozilla/remo,Mte90/remo,Mte90/remo,tsmrachel/remo,flamingspaz/remo,Mte90/remo,tsmrachel/remo,Mte90/remo,akatsoulas/remo