Fix type error in `cmd/cleanup`.
Fix type error in `cmd/cleanup`.

JCount/brew,JCount/brew,nandub/brew,vitorgalvao/brew,konqui/brew,JCount/brew,sjackman/homebrew,sjackman/homebrew,konqui/brew,EricFromCanada/brew,Homebrew/brew,EricFromCanada/brew,Homebrew/brew,vitorgalvao/brew,Homebrew/brew,EricFromCanada/brew,sjackman/homebrew,Homebrew/brew,nandub/brew,claui/brew,vitorgalvao/brew,claui/brew,claui/brew,nandub/brew,vitorgalvao/brew,claui/brew,MikeMcQuaid/brew,sjackman/homebrew,konqui/brew,EricFromCanada/brew,MikeMcQuaid/brew,JCount/brew,MikeMcQuaid/brew,konqui/brew,nandub/brew,MikeMcQuaid/brew