FindPython: fix for libs on windows

In windows, the library folder usually ends up in the path:

C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.9_3.9.2544.0_x64__qbz5n2kfra8p0\Lib

or

C:\Program Files\Python310\Lib

and not in {prefix}/lib/python{major}.{minor} as the python documentation used to say.

I've raised a bug against the documentation here - https://bugs.python.org/issue45788 which was fixed.