eCAL 5.9.6

Changelog

# Changes

CMake:
- Surrounded MSVC specific Qt5 autodetection code with if(MSVC)

Python:
- User-Callback-Errors are now printed to console
- Compatibility fix with Python 3.10
- Fixed a bug that could cause Protobuf descriptors being added to the database multiple times
- Re-generated sample pb2.py files, so they are now compatible down to protobuf 3.0

eCAL 5.9.6 is patch-level equivalent to eCAL 5.8.19