You seem to have an issue with an old Python installation that wasn't fully removed.
An easy way to resolve it is by overwriting the system PATH
variable.
Press Winkey+Break (or Winkey+Pause depending on keyboard), go to "advanced system settings" then "environment variables".
On user variables you have "path". Edit it and add this new path:
C:Users<user>AppDataLocalProgramsPythonPython39Scripts
Move this all the way to the top and press OK.
Reopen your cmd. Should work.
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