chore(travis): fix dropbox_key in windows build
chore(travis): fix dropbox_key in windows build

rlewis1988/lean,avigad/lean,eigengrau/lean,soonhokong/lean-windows,fpvandoorn/lean,Kha/lean,leodemoura/lean,soonhokong/travis_test,soonhokong/lean-osx,leanprover/lean,digama0/lean,digama0/lean,soonhokong/travis_test,leanprover/lean,digama0/lean,c-cube/lean,UlrikBuchholtz/lean,fgdorais/lean,codyroux/lean0.1,soonhokong/lean-osx,dselsam/lean,johoelzl/lean,leanprover-community/lean,leanprover-community/lean,c-cube/lean,soonhokong/lean,leanprover/lean,leanprover-community/lean,fpvandoorn/lean2,Kha/lean,UlrikBuchholtz/lean,levnach/lean,javra/lean,soonhokong/lean-windows,sp3ctum/lean,soonhokong/travis_test,leanprover-community/lean,Kha/lean,htzh/lean,johoelzl/lean,c-cube/lean,johoelzl/lean,c-cube/lean,soonhokong/lean,sp3ctum/lean,rlewis1988/lean,leodemoura/lean,soonhokong/lean,leodemoura/lean,eigengrau/lean,UlrikBuchholtz/lean,levnach/lean,dselsam/lean,codyroux/lean0.1,fgdorais/lean,avigad/lean,leanprover/lean,leanprover-community/lean,eigengrau/lean,fpvandoorn/lean2,c-cube/lean,javra/lean,fpvandoorn/lean,sp3ctum/lean,avigad/lean,codyroux/lean0.1,fpvandoorn/lean2,fpvandoorn/lean2,levnach/lean,Kha/lean,levnach/lean,rlewis1988/lean,fgdorais/lean,soonhokong/lean-osx,fpvandoorn/lean,eigengrau/lean,fpvandoorn/lean,johoelzl/lean,leanprover/lean,sp3ctum/lean,levnach/lean,javra/lean,Kha/lean,UlrikBuchholtz/lean,fgdorais/lean,fpvandoorn/lean,soonhokong/lean,fgdorais/lean,leodemoura/lean,sp3ctum/lean,digama0/lean,Kha/lean,dselsam/lean,fpvandoorn/lean2,codyroux/lean0.1,soonhokong/lean-windows,leanprover-community/lean,soonhokong/lean-osx,fpvandoorn/lean,rlewis1988/lean,htzh/lean,soonhokong/lean-windows,javra/lean,leodemoura/lean,soonhokong/lean,UlrikBuchholtz/lean,johoelzl/lean,rlewis1988/lean,htzh/lean,soonhokong/lean-windows,htzh/lean,fgdorais/lean,leanprover/lean,avigad/lean,dselsam/lean,avigad/lean,avigad/lean,dselsam/lean,soonhokong/travis_test,rlewis1988/lean,dselsam/lean,htzh/lean,eigengrau/lean,johoelzl/lean,digama0/lean,javra/lean,leodemoura/lean,digama0/lean,soonhokong/lean-osx