Error after trying to use pdfkit in google app engine

Question

I'm trying to generate a pdf from html in google app engine, I used the same configuration that I used on Heroku

if platform.system() == "Windows":
        config = pdfkit.configuration(wkhtmltopdf=os.environ.get('WKHTMLTOPDF_BINARY', 'C:\\Program Files\\wkhtmltopdf\\bin\\wkhtmltopdf.exe'))
else:
        os.environ['PATH'] += os.pathsep + os.path.dirname(sys.executable)
        WKHTMLTOPDF_CMD = subprocess.Popen(['which', os.environ.get('WKHTMLTOPDF_BINARY', 'wkhtmltopdf')],
            stdout=subprocess.PIPE).communicate()[0].strip()
        config = pdfkit.configuration(wkhtmltopdf=WKHTMLTOPDF_CMD) 

And also added this in app.yaml file

env_variables:
  WKHTMLTOPDF_BINARY: wkhtmltopdf-pack

but I'm getting this error

/env/bin/wkhtmltopdf-pack: error while loading shared libraries: libXrender.so.1: cannot open shared object file: No such file or directory

I tried to install libXrender.so.1 by using this command

sudo apt-get install -y libxrender1

but it saying that I have already installed libxrender1

libxrender1 is already the newest version (1:0.9.10-1).

Am I missing something, or maybe this config cannot be used with google?