Update dropbox-beta from 98.3.151 to 99.3.488 (#9136)
Update dropbox-beta from 98.3.151 to 99.3.488 (#9136)


rogeriopradoj/homebrew-versions,404NetworkError/homebrew-versions,caskroom/homebrew-versions,caskroom/homebrew-versions,pkq/homebrew-versions,pkq/homebrew-versions,rogeriopradoj/homebrew-versions,404NetworkError/homebrew-versions,mahori/homebrew-cask-versions