La génération des images de famille renvoie une erreur 500

Par exemple sur mon compte : https://ae.utbm.fr/user/18763/godfathers/tree/pict?family

En local, on obtient ça :

ModuleNotFoundError at /user/0/godfathers/tree/pict
No module named 'pygraphviz'
Request Method:	GET
Request URL:	http://127.0.0.1:8000/user/0/godfathers/tree/pict?family
Django Version:	2.2.28
Exception Type:	ModuleNotFoundError
Exception Value:	
No module named 'pygraphviz'
Exception Location:	/Users/theod/PycharmProjects/Sith/core/views/user.py in build_family_graph, line 446
Python Executable:	/Users/theod/Library/Caches/pypoetry/virtualenvs/sith-xyfLMp1S-py3.9/bin/python
Python Version:	3.9.12
Python Path:	
[...]
Server time:	dim, 8 Mai 2022 10:35:31 +0200