Add github mirror for the download extension

    return url

def install_extension_from_url(dirname, url, branch_name=None):

def install_extension_from_url(dirname, proxy, url, branch_name=None):

    check_access()

    assert url, 'No URL specified'

    proxy_list = {

        "none": "",

        "ghproxy": "https://ghproxy.com/",

        "hub.yzuu.cf": "https://hub.yzuu.cf/",

        "hub.njuu.cf": "https://hub.njuu.cf/",

        "hub.nuaa.cf": "https://hub.nuaa.cf/",

    }

    url = proxy_list[proxy] + url

    if dirname is None or dirname == "":

        *parts, last_part = url.split('/')

        last_part = normalize_git_url(last_part)

        shutil.rmtree(tmpdir, True)

        if not branch_name:

            # if no branch is specified, use the default branch

            with git.Repo.clone_from(url, tmpdir, filter=['blob:none']) as repo:

            with git.Repo.clone_from(url, tmpdir, filter=['blob:none'], verbose=False) as repo:

                repo.remote().fetch()

                for submodule in repo.submodules:

                    submodule.update()

        else:

            with git.Repo.clone_from(url, tmpdir, filter=['blob:none'], branch=branch_name) as repo:

            with git.Repo.clone_from(url, tmpdir, filter=['blob:none'], branch=branch_name, verbose=False) as repo:

                repo.remote().fetch()

                for submodule in repo.submodules:

                    submodule.update()

                )

            with gr.TabItem("Install from URL", id="install_from_url"):

                install_proxy = gr.Radio(

                    label="Install Proxy", choices=["none", "ghproxy", "hub.nuaa.cf","hub.yzuu.cf","hub.njuu.cf"], value="none", 

                    info="If you can't access github.com, you can use a proxy to install extensions from github.com"

                )

                install_url = gr.Text(label="URL for extension's git repository")

                install_branch = gr.Text(label="Specific branch name", placeholder="Leave empty for default main branch")

                install_dirname = gr.Text(label="Local directory name", placeholder="Leave empty for auto")

                install_button.click(

                    fn=modules.ui.wrap_gradio_call(lambda *args: [gr.update(), *install_extension_from_url(*args)], extra_outputs=[gr.update(), gr.update()]),

                    inputs=[install_dirname, install_url, install_branch],

                    inputs=[install_dirname, install_proxy, install_url, install_branch],

                    outputs=[install_url, extensions_table, install_result],

                )