fix getting System.MissingMethodException in .NET test
fix getting System.MissingMethodException in .NET test

When testing in Python 3.9 and pythonnet 3.0.0.dev1 the following error was raised "System.MissingMethodException: No parameterless constructor defined for this object"

MSLNZ/msl-loadlib,MSLNZ/msl-loadlib,MSLNZ/msl-loadlib,MSLNZ/msl-loadlib,MSLNZ/msl-loadlib