ModuleNotFoundError: No module named 'multiprocessing'

Please review the Troubleshooting section before reporting any issue. Don't forget to check also the current issues to avoid duplicates.

Subject of the issue

Describe your issue here.

Traceback (most recent call last):
  File "c:\\\users\test\appdata\local\programs\python\python39\lib\runpy.py", line 197, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "c:\\\users\test\appdata\local\programs\python\python39\lib\runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "C:\Users\test\AppData\Local\Programs\Python\Python39\Scripts\coursera-dl.exe\__main__.py", line 4, in <module>
  File "c:\\\users\test\appdata\local\programs\python\python39\lib\site-packages\coursera\coursera_dl.py", line 67, in <module>
    from .parallel import ConsecutiveDownloader, ParallelDownloader
  File "c:\\\users\test\appdata\local\programs\python\python39\lib\site-packages\coursera\parallel.py", line 4, in <module>
    from multiprocessing.dummy import Pool
ModuleNotFoundError: No module named 'multiprocessing'

Your environment

• Operating System (name/version): Windows 10
• Python version: 3.9
• coursera-dl version: last (installed with pip)

Steps to reproduce

Tell us how to reproduce this issue, please don't forget to include enough information so that you can help us help you:

• Is the problem happening with the latest version of the script? Yes
• Do you have all the recommended versions of the modules? See them in the file requirements.txt. yes
• What is the course that you are trying to access? even coursera-dl --help doesnt work fundamentals-of-graphic-design_
• What is the precise command line that you are using (don't forget to obfuscate your username and password, but leave all other information untouched). coursera-dl -u user -p password fundamentals-of-graphic-design
• What are the precise messages that you get? Please, use the --debug option before posting the messages as a bug report. Please, copy and paste them. Don't reword/paraphrase the messages. same error as above

Expected behaviour

Tell us what should happen. Coursera-dl should work

Actual behaviour

Tell us what happens instead. If the script fails, please copy the entire output of the command or the stacktrace (don't forget to obfuscate your username and password). If you cannot copy the exception, attach a screenshot. Doesn't work at all