Update shacl2code and release new spdx-python-model with improved IDE support

[bact]

Use new shacl2code (post-v1.0.0) for improved type support and developer ergonomic (will help developers getting around case like one in #27)

[benjarobin]

To release the next version of spdx-python-model (0.0.5?), we must wait for the next release of shacl2code. Version 1.0.0 cannot/should not be used, since it has one bug (quite major) and the generate Python stub is broken.