brew替换成国内源

cd "$(brew --repo)"  
git remote set-url origin https://mirrors.ustc.edu.cn/brew.git  
cd "$(brew --repo)/Library/Taps/homebrew/homebrew-core"  
git remote set-url origin https://mirrors.ustc.edu.cn/homebrew-core.git  
cd "$(brew --repo)/Library/Taps/homebrew/homebrew-cask"  
git remote set-url origin https://mirrors.ustc.edu.cn/homebrew-cask.git