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("""
ERROR! --version-suffix needs parameter!
""", file=sys.stderr)
            usage()
            sys.exit(1)
        suffix = sys.argv[2]
        sys.argv = [sys.argv[0]] + sys.argv[3:]
    elif "--help" in sys.argv or "-h" in sys.argv or len(sys.argv) < 2:
        usage()
        sys.exit(0)
    if sys.argv[1] not in possible_first_params:
        print(f"""
ERROR! Wrong first param: {sys.argv[1]}
""", file=sys.stderr)
        usage()
        print()
        sys.exit(1)
    if sys.argv[1] == LIST_PROVIDERS_PACKAGES:
        providers = PROVIDERS_REQUIREMENTS.keys()
        for provider in providers:
            print(provider)
        sys.exit(0)
    elif sys.argv[1] == LIST_BACKPORTABLE_PACKAGES:
        providers = get_all_backportable_providers()
        for provider in providers:
            print(provider)
        sys.exit(0)
    elif sys.argv[1] == UPDATE_PACKAGE_RELEASE_NOTES:
        release_ver = ""
        if len(sys.argv) > 2 and re.match(r'\d{4}\.\d{2}\.\d{2}', sys.argv[2]):