3.0.1

Including suggestions made by @blsqr:

Update development status to beta
Test now fail if there is any warning message
The tests that were still working with unittest have been moved to pytest
Test and add support for Python 3.10
Improve the test documentation
Move from SourceFileLoader.load_module() to importlib.util.spec_from_file_location.loader.exec_module() to avoid deprecation in Python 3.12
Correct some other warnings

Bug correction:

TabData objects' coordinates now are simplified in the model file, using the _subscript_dict as other objects.