Hello,

Slack has released updates to its library and we can start using it for it. 

We especially like one change.

> slack_sdk has no required dependencies. This means aiohttp is no longer automatically resolved.

I've looked through the documentation and it doesn't look like a difficult task, but I think it's still worth testing.
More info: https://slack.dev/python-slack-sdk/v3-migration/index.html#from-slackclient-2-x

Best regards,
Kamil Breguła
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()
EXTRAS_WITH_PROVIDERS: Set[str] = set()
PREINSTALLED_PROVIDERS = [
    'ftp',
    'http',
    'imap',
    'sqlite',
]
def get_provider_package_from_package_id(package_id: str):
    """
    Builds the name of provider package out of the package id provided/
    :param package_id: id of the package (like amazon or microsoft.azure)
    :return: full name of package in PyPI
    """
    package_suffix = package_id.replace(".", "-")
    return f"apache-airflow-providers-{package_suffix}"
class AirflowDistribution(Distribution):