remove unused variable filename in test_unpack_picklable
remove unused variable filename in test_unpack_picklable

lamblin/fuel,dwf/fuel,jbornschein/fuel,orhanf/fuel,aalmah/fuel,rodrigob/fuel,dhruvparamhans/fuel,glewis17/fuel,laurent-dinh/fuel,udibr/fuel,markusnagel/fuel,glewis17/fuel,jbornschein/fuel,bouthilx/fuel,udibr/fuel,rizar/fuel,dmitriy-serdyuk/fuel,harmdevries89/fuel,dmitriy-serdyuk/fuel,chrishokamp/fuel,bouthilx/fuel,orhanf/fuel,dwf/fuel,EderSantana/fuel,vdumoulin/fuel,ejls/fuel,ejls/fuel,codeaudit/fuel,lamblin/fuel,janchorowski/fuel,hantek/fuel,markusnagel/fuel,laurent-dinh/fuel,codeaudit/fuel,dhruvparamhans/fuel,aalmah/fuel,dribnet/fuel,rizar/fuel,hantek/fuel,dribnet/fuel,capybaralet/fuel,harmdevries89/fuel,mila-udem/fuel,chrishokamp/fuel,janchorowski/fuel,EderSantana/fuel,rodrigob/fuel,mila-udem/fuel,vdumoulin/fuel,capybaralet/fuel,mjwillson/fuel,mjwillson/fuel