Linux（八）：解决brew错误 - unknown or unsupported macOS version: :dunno (MacOSVersionError)

错误

> brew
/usr/local/Homebrew/Library/Homebrew/os/mac/version.rb:33:in `block in from_symbol': unknown or unsupported macOS version: :dunno (MacOSVersionError)
  from /usr/local/Homebrew/Library/Homebrew/os/mac/version.rb:33:in `fetch'
  from /usr/local/Homebrew/Library/Homebrew/os/mac/version.rb:33:in `from_symbol'
  from /usr/local/Homebrew/Library/Homebrew/os/mac.rb:28:in `version'
  from /usr/local/Homebrew/Library/Homebrew/os/mac.rb:60:in `prerelease?'
  from /usr/local/Homebrew/Library/Homebrew/os.rb:43:in `<module:OS>'
  from /usr/local/Homebrew/Library/Homebrew/os.rb:7:in `<top (required)>'
  from /usr/local/Homebrew/Library/Homebrew/global.rb:79:in `require'
  from /usr/local/Homebrew/Library/Homebrew/global.rb:79:in `<top (required)>'
  from /usr/local/Homebrew/Library/Homebrew/brew.rb:31:in `require_relative'
  from /usr/local/Homebrew/Library/Homebrew/brew.rb:31:in `<main>'

解决

brew update-reset