FileGrouper issue: TypeError: __init__() got an unexpected keyword argument 'capture_output'

[root@d7cad70685bc transfer_service]# python3 
Python 3.6.8 (default, Apr 16 2020, 01:36:27) 
[GCC 8.3.1 20191121 (Red Hat 8.3.1-5)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from filegrouper import FileGrouper
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ModuleNotFoundError: No module named 'filegrouper'
>>> from file_grouper import FileGrouper
>>> fg = FileGrouper(0, 100 * (2 ** 30))
>>> fg.recursive("/home/curban/store")                     
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/transfer_service/file_grouper.py", line 55, in recursive
    sp = subprocess.run(["tar", "-cf", os.path.basename(folder) + ".tar", os.path.basename(folder)], capture_output = True)
  File "/usr/lib64/python3.6/subprocess.py", line 423, in run
    with Popen(*popenargs, **kwargs) as process:
TypeError: __init__() got an unexpected keyword argument 'capture_output'

The capture_output parameter was introduced starting from Python 3.7.

CentOS 8 Python 3 version is 3.6.8.