Update skype-preview to 8.21.76.6 (#5657)
Update skype-preview to 8.21.76.6 (#5657)


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