现在代理支持以下两种形式，之前只支持第二种

$client->request('GET', '/', ['proxy' => 'http://localhost:8125']);

$client->request('GET', '/', [
    'proxy' => [
        'http'  => 'tcp://localhost:8125', // Use this proxy with "http"
        'https' => 'tcp://localhost:9124', // Use this proxy with "https",
        'no' => ['.mit.edu', 'foo.com']    // Don't use a proxy with these
    ]
]);