unexpected keyword

[Konfekt]

Using the current master branch, after installing the Python dependencies, there is the following error message:

pip install --user -r requirements.txt

Installing collected packages: py3-progressbar, pycrypto
  Running setup.py install for py3-progressbar ... done
  Running setup.py install for pycrypto ... done
Successfully installed py3-progressbar-2.4.dev0 pycrypto-2.6.1
You are using pip version 10.0.1, however version 19.0.3 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
pip install --user -r requirements.txt  25,02s user 2,56s system 96% cpu 28,439 total

python3 mass_apk_installer.py backup

Traceback (most recent call last):
  File "mass_apk_installer.py", line 558, in <module>
    command, args = parse_args()
  File "mass_apk_installer.py", line 339, in parse_args
    required=True, dest="command", help="command help"
  File "/usr/lib64/python3.6/argparse.py", line 1703, in add_subparsers
    action = parsers_class(option_strings=[], **kwargs)
TypeError: __init__() got an unexpected keyword argument 'required'