If removing trailing slashes from the environment variables don’t work, please try the following.
It works fine for me.
I am using window 10 and python3.7.0
Advanced system settings -> Environment Variables -> Path
Select Edit
Select Move Up button for both python and Scripts directory.
Finally your path will be as the following.
If you are using other window version(In the case of not having move up
button), put your python and Scripts directory at the beginning of
the path.