Fix kemono.su Api Endpoint & Add Http Proxy

[Ovear]

Hi,

Thanks for contributing & letting me know the changes of APIs. But it's not good to hardcode proxy server in the code.

And actually, it won't need to touch code. You may use HTTP_PROXY and HTTPS_PROXY environment variable to set proxy.

I have also introduced an not standard proxy called proxy agent, please feel free to check it if you are interested in.