Windows first run fails with Unsupported OS/platform 'win64'

### Description

Installed Python 3.6 and put on my path. Ran scancode the first time and it errors out.

### How To Reproduce

Unzip and run scancode:

```
* Configuring ScanCode for first use...
Python 3.6.8
C:\Users\daveb\AppData\Local\Programs\Python\Python36-32\python.exe
Junction created for C:\Users\daveb\Downloads\scancode-toolkit-3.1.1\bin <<===>> C:\Users\daveb\Downloads\scancode-toolkit-3.1.1\Scripts
Unsupported OS/platform 'win64'.
See https://github.com/nexB/scancode-toolkit/ for supported OS/platforms.
Enter a ticket https://github.com/nexB/scancode-toolkit/issues asking for support of your OS/platform combo.
Traceback (most recent call last):
File "C:\Users\daveb\Downloads\scancode-toolkit-3.1.1\etc\configure.py", line 574, in
run_scripts(configs, root_dir, configured_python, quiet=quiet)
File "C:\Users\daveb\Downloads\scancode-toolkit-3.1.1\etc\configure.py", line 322, in run_scripts
call(cmd, root_dir)
File "C:\Users\daveb\Downloads\scancode-toolkit-3.1.1\etc\configure.py", line 137, in call
subprocess.check_call(cmd, shell=True, env=dict(os.environ), cwd=root_dir)
File "C:\Python27\lib\subprocess.py", line 190, in check_call
raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '"C:\Users\daveb\Downloads\scancode-toolkit-3.1.1\bin\python.exe" "C:\Users\daveb\Downloads\scancode-toolkit-3.1.1\etc\conf\base.py"' returned non-zero exit status 1
```

### System configuration

Windows version 10 19042.421
Scancode 3.1.1
Installed with unzip & running scancode from cmd.exe