The comment of juanpa.arrivillega solves my problem:

"python package names are case insensitive, and on pypi, the "modAL" package seems to be distributed as "modAL-python""

I just replaced "modAL" by "modAL-python" and it works as expected. Thank you !

Can you add it as a regular answer so I can accept it ?

NOTE : Meanwhile I asked ChatGPT which suggested to use Poetry, but I couldn't find the right way to add this dependency line.