Get ready for release 9.0.0

[rocky]

No description provided.

[mmatera]

@rocky, after all this noise, I think now it works. There was two problems:

• setuptools seems to be installed before stopit (a dependency from Mathics-core) before the installation starts.
• the module pymathics.natlang is not available until the dependencies (like spacy) are installed. So we have to look the version number directly from pymathics.natlang.version.__version__

[rocky]

@mmatera thanks!