the Visual Studio 2015 image wasn't compatible with pacman anymore. Upgraded it to VS 2019 and its specific dependencies (boost 1.73 and the current VS redistributables);
Updated supported Python versions: removed 3.6 and added 3.8;
In Python 3.8 the .pyd/.dll file import mechanism was changed. Implemented the necessary modifications to support pysmu's importing for Python 3.8.
updated libusb version to 1.0.23; v1.0.24 is not compatible with the Python bindings because it defines some symbols which conflicts with the Python libraries;
dpinst.exe is not supported in the latest Windows 10 releases; changed it with pnputil.exe;
iscc removed some language packages; I removed them from out installer as well;
removed some redundant commands from the appveyor.yml file.
The following changes were made: