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
"""
    For Python 3.6+ the dictionary order remains when keys() are retrieved.
    Sort both: extras and list of dependencies to make it easier to analyse problems
    external packages will be first, then if providers are added they are added at the end of the lists.
    """
    sorted_requirements = dict(sorted(EXTRAS_REQUIREMENTS.items()))
    for extra_list in sorted_requirements.values():
        extra_list.sort()
    return sorted_requirements
EXTRAS_REQUIREMENTS = sort_extras_requirements()
PREINSTALLED_PROVIDERS = [
    'ftp',
    'http',
    'imap',
    'sqlite',
]
def get_provider_package_from_package_id(package_id: str) -> str: