bump leveldown dev dependency
bump leveldown dev dependency

djchie/levelup,Level/levelup,roppa/levelup,JTKnox91/levelup,toddself/levelup,toddself/levelup,lastguest/levelup,roppa/levelup,lastguest/levelup,JTKnox91/levelup,djchie/levelup,timkuijsten/levelup,timkuijsten/levelup