mac下 Homebrew 可能会在install或者update的时候会很慢，卡很久。
两种方式来解决：
一、直接关闭brew执行命令时的自动更新
# 1. 编辑配置文件
vim ~/.bash_profile
# 2. 文件内新增一行
export HOMEBREW_NO_AUTO_UPDATE=true
# 3. 重新加载配置文件
source ~/.bash_profile
二、替换brew源
cd "$(brew --repo)"
git remote set-url origin https://mirrors.ustc.edu.cn/brew.git
#替换homebrew-core.git
cd "$(brew --repo)/Library/Taps/homebrew/homebrew-core"
git remote set-url origin https://mirrors.ustc.edu.cn/homebrew-core.git
brew update
# 备用地址-1
cd "$(brew --repo)"
git remote set-url origin https://git.coding.net/homebrew/homebrew.git
brew update
# 备用地址-2
cd "$(brew --repo)"
git remote set-url origin https://mirrors.tuna.tsinghua.edu.cn/git/brew.git
cd "$(brew --repo)/Library/Taps/homebrew/homebrew-core"
git remote set-url origin https://mirrors.tuna.tsinghua.edu.cn/git/homebrew-core.git
brew update
PS：官方默认信息
# 1. 重置brew.git
cd "$(brew --repo)"
git remote set-url origin https://github.com/Homebrew/brew.git
# 2. 重置homebrew-core.git
cd "$(brew --repo)/Library/Taps/homebrew/homebrew-core"
git remote set-url origin https://github.com/Homebrew/homebrew-core.git
