Как указать версию клиента в скрипте?

import sys
import time
from PyQt4.QtCore import *
from PyQt4.QtGui import *
from PyQt4.QtWebKit import *


class MakeScreenshot(QWebView):
    def __init__(self):
        self.app = QApplication(sys.argv)
        QWebView.__init__(self)
        self._loaded = False
        self.loadFinished.connect(self._loadFinished)

    def wait_load(self, delay=0):
        while not self._loaded:
            self.app.processEvents()
            time.sleep(delay)
        self.loaded = False

    def _loadFinished(self, result):
        self._loaded = True

    def get_image(self, url):
        self.load(QUrl(url))
        self.wait_load()

        frame = self.page().mainFrame()
        self.page().setViewportSize(frame.contentsSize())

        image = QImage(self.page().viewportSize(),
                       QImage.Format_ARGB32)
        painter = QPainter(image)
        frame.render(painter)
        painter.end()
        return image

s = MakeScreenshot()
image = s.get_image('https://yandex.ru/')
image.save('website-screen6.png')