ssh provider has limit to sshtunnel  < 0.2
https://github.com/apache/airflow/blob/9d6ae609b60449bd274c2f96e72486d73ad2b8f9/setup.py#L451

I don't know why? sshtunnel  already released 0.4
I didn't open PR because I don't know this provider i just tried to install it and couldn't due to conflicts with other requirements in my system so eventually i used vitrual env to solve my problem but logging this issue so that someone who knows this code can handle it.
setup.py
When installing providers from sources we install all namespace packages found below airflow,
        including airflow and provider packages, otherwise defaults from setup.cfg control this.
        The kwargs in setup() call override those that are specified in setup.cfg.
        """
        if os.getenv(INSTALL_PROVIDERS_FROM_SOURCES) == 'true':
            setup_kwargs['packages'] = find_namespace_packages(include=['airflow*'])
    include_provider_namespace_packages_when_installing_from_sources()
    if os.getenv(INSTALL_PROVIDERS_FROM_SOURCES) == 'true':
        print("Installing providers from sources. Skip adding providers as dependencies")
    else:
        add_all_provider_packages()
    write_version()
    setup(
        distclass=AirflowDistribution,
        version=version,
        extras_require=EXTRAS_REQUIREMENTS,
        download_url=('https://archive.apache.org/dist/airflow/' + version),
        cmdclass={
            'extra_clean': CleanCommand,
            'compile_assets': CompileAssets,
            'list_extras': ListExtras,
            'install': Install,
            'develop': Develop,
        },
        test_suite='setup.airflow_test_suite',
        **setup_kwargs,
    )
if __name__ == "__main__":
    do_setup()  # co