Update brave-browser-nightly.rb (#7897)
Update brave-browser-nightly.rb (#7897)

Changed the file to point to the latest version in the appcast, which is the bottom-most link.
caskroom/homebrew-versions,lantrix/homebrew-versions,caskroom/homebrew-versions,lantrix/homebrew-versions,victorpopkov/homebrew-versions,rogeriopradoj/homebrew-versions,Ngrd/homebrew-versions,rogeriopradoj/homebrew-versions,404NetworkError/homebrew-versions,404NetworkError/homebrew-versions,pkq/homebrew-versions,victorpopkov/homebrew-versions,pkq/homebrew-versions,Ngrd/homebrew-versions,mahori/homebrew-cask-versions