Windows build busted with missing \Python3\ directory

[earlephilhower]

Opening for @mikekgr.

The Python3 merge broke Windows due to a renaming of the installed python directory.

See for full details: #6378 (comment)

Either the python.zip file for Windows needs to be moved on the toolchain dir to \python3\ (simplest), or the platform.txt needs to not use {python} as the subdir.

[earlephilhower]

@mikekgr, please give #6472 a try. You will need to re-execute get.py and it will download a properly named python3-xxx.zip file and install into the appropriate spot. No renaming should be needed.

[mikekgr]

Dear @earlephilhower , I happily confirm that it is working fine now. Many many thanks !

[earlephilhower]

Merged and confirmed. Closing.