ctypes.c_byte to ctypes.c_ubyte fix

[sjarman28]

ctypes.c_byte is specified to be equivalent to a signed char (-128 to 127) but we were passing unsigned char values (0-255) so we should be using ctypes.c_ubyte: https://docs.python.org/3/library/ctypes.html#ctypes.c_byte

This issue causes some of our functions to throw exceptions when using IronPython.