Pin django-waffle given it's broken currently.
Pin django-waffle given it's broken currently.

This may only be temporary but I don't think we have the bandwidth to
help upstream fix it so let's pin it for now until we do.

Closes #9882

wagnerand/olympia,mozilla/addons-server,bqbn/addons-server,diox/olympia,kumar303/olympia,aviarypl/mozilla-l10n-addons-server,mozilla/addons-server,bqbn/addons-server,mozilla/olympia,wagnerand/olympia,kumar303/olympia,mozilla/addons-server,eviljeff/olympia,aviarypl/mozilla-l10n-addons-server,kumar303/addons-server,psiinon/addons-server,wagnerand/addons-server,wagnerand/addons-server,eviljeff/olympia,kumar303/addons-server,psiinon/addons-server,mozilla/olympia,mozilla/olympia,wagnerand/olympia,diox/olympia,bqbn/addons-server,wagnerand/addons-server,kumar303/addons-server,mozilla/olympia,kumar303/olympia,kumar303/addons-server,aviarypl/mozilla-l10n-addons-server,kumar303/olympia,wagnerand/addons-server,mozilla/addons-server,diox/olympia,eviljeff/olympia,psiinon/addons-server,psiinon/addons-server,wagnerand/olympia,bqbn/addons-server,eviljeff/olympia,diox/olympia,aviarypl/mozilla-l10n-addons-server