Fix `brew cask outdated` deprecations
Fix `brew cask outdated` deprecations

- A lot of the separation between Homebrew formulae and casks was
  deprecated in [Homebrew 2.5.0](https://brew.sh/2020/09/08/homebrew-2.5.0/),
  released last week. To avoid `brew bundle` showing deprecation warnings
  to users, update the invocations.

Homebrew/homebrew-bundle