Install SDF library

This library is not (yet) published on pypi.org, so, in order to install it, you will have to manually download it:

1. Download zip file https://github.com/fogleman/sdf/archive/refs/heads/main.zip
2. Unpack it to some directory, for example, ~/src/sdf
3. Install it into Blender's python with pip:

$ /path/to/blender/2.xx/python/bin/python3.7m -m pip install ~/src/sdf