README.python.md: Add some notes for Windows Note that the DLLs for HarfBuzz and its deps must be found %PATH% on Windows so that pygobject is able to import and use HarfBuzz in Python scripts. Also note that for Visual Studio builds, it is recommended that Visual Studio 2019 or later is used for the build, possibly in regards with how the preprocessor handles C++ code when running g-ir-scanner.