Can't find model 'en_core_web_sm'

Hi!

I get the error
```
cd </path/to/bionicpython/src>/bionicpython
python bionicpython.py ../test.pdf
...
[INFO] [4/4] Creating pages...
...
[INFO] (21/21) Page 21
[INFO] Terminated in 56.74s.
Error loading spaCy model: [E050] Can't find model 'en_core_web_sm'. It doesn't seem to be a Python package or a valid path to a data directory.
```

Thanks for help and cheers,
Chris