zsh completions: add brew cask upgrade
zsh completions: add brew cask upgrade

nandub/brew,reitermarkus/brew,reitermarkus/brew,ilovezfs/brew,mgrimes/brew,Linuxbrew/brew,JCount/brew,EricFromCanada/brew,mgrimes/brew,ilovezfs/brew,mahori/brew,JCount/brew,vitorgalvao/brew,Homebrew/brew,nandub/brew,Homebrew/brew,maxim-belkin/brew,claui/brew,konqui/brew,EricFromCanada/brew,reitermarkus/brew,nandub/brew,DomT4/brew,mahori/brew,claui/brew,reitermarkus/brew,maxim-belkin/brew,MikeMcQuaid/brew,Homebrew/brew,EricFromCanada/brew,claui/brew,Homebrew/brew,EricFromCanada/brew,vitorgalvao/brew,JCount/brew,sjackman/homebrew,vitorgalvao/brew,mgrimes/brew,DomT4/brew,DomT4/brew,vitorgalvao/brew,Linuxbrew/brew,MikeMcQuaid/brew,sjackman/homebrew,sjackman/homebrew,DomT4/brew,Linuxbrew/brew,MikeMcQuaid/brew,mahori/brew,sjackman/homebrew,nandub/brew,konqui/brew,konqui/brew,JCount/brew,mahori/brew,claui/brew,konqui/brew,MikeMcQuaid/brew,maxim-belkin/brew,ilovezfs/brew,Linuxbrew/brew