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
current_release_version: str,
                          current_changes: str,
                          backport_packages: bool) -> None:
    """
    Stores current changes in the BACKPORT_PROVIDERS_CHANGES_YYYY.MM.DD.md file.
    :param provider_package_path: path for the package
    :param current_release_version: release version to build
    :param current_changes: list of changes formatted in markdown format
    :param backport_packages: whether to prepare regular (False) or backport (True) packages
    """
    current_changes_file_path = os.path.join(
        provider_package_path,
        get_provider_changes_prefix(backport_packages=backport_packages) + current_release_version + ".md")
    with open(current_changes_file_path, "wt") as current_changes_file:
        current_changes_file.write(current_changes)
        current_changes_file.write("\n")
def get_package_path(provider_package_id: str) -> str:
    """
    Retrieves package path from package id.
    :param provider_package_id: id of the package
    :return: path of the providers folder
    """
    provider_package_path = os.path.join(PROVIDERS_PATH, *provider_package_id.split("."))
    return provider_package_path
def get_additional_package_info(provider_package_path: str) -> str: