The dependencies in Alphas are currently >= 2.0.0 and should be >=2.0.0a0 in order to work with Alphas in cases which are not PEP 440-compliant.

According to https://www.python.org/dev/peps/pep-0440/, >= 2.0.0 should also work with alpha/beta releases (a1/a2) but in some cases it does not (https://apache-airflow.slack.com/archives/C0146STM600/p1602774750041800) 

Changing to ">=2.0.0a0" should help.
provider_packages/setup_provider_packages.py
print(f"ERROR! There are {bad} errors of {total} entities for {provider_package_id}")
        print()
    return total, bad
def update_release_notes_for_packages(provider_ids: List[str],
                                      release_version: str,
                                      backport_packages: bool):
    """
    Updates release notes for the list of packages specified.
    :param provider_ids: list of provider ids
    :param release_version: version to release
    :param backport_packages: whether to prepare regular (False) or backport (True) packages
    :return:
    """
    imported_classes = import_all_provider_classes(
        source_path=SOURCE_DIR_PATH, provider_ids=provider_ids, print_imports=False)
    make_sure_remote_apache_exists_and_fetch()
    if len(provider_ids) == 0:
        if backport_packages:
            provider_ids = get_all_backportable_providers()
        else:
            provider_ids = get_all_providers()
    total = 0
    bad = 0
    print()
    print("Generating README files and checking if entities are correctly named.")
    print()
    print("Providers to generate:")
    for provider_id in provider_ids:
        print(provider_id)
    print()