Install PHP Extension for PHP 5.

Because php 5.6 is EOL from 01.01.2019, it was removed from homebrew.

brew tap exolnet/homebrew-deprecated

#更新exolnet/homebrew-deprecated到本地环境
Cloning into '/usr/local/Homebrew/Library/Taps/exolnet/homebrew-deprecated'...
remote: Enumerating objects: 11, done.
remote: Counting objects: 100% (11/11), done.
remote: Compressing objects: 100% (11/11), done.
remote: Total 11 (delta 1), reused 7 (delta 0), pack-reused 0
Unpacking objects: 100% (11/11), done.
Tapped 2 formulae (42 files, 78.2KB).

#安装deprecated版本
brew install php@5.6

#切换PHP版本
brew-php-switcher 5.6#需要安装brew-php-switcher(brew install brew-php-switcher)