Generating self-signed certificates via docker-compose fails

Generating self-signed certificates via docker-compose and docker-compose.icessl.yml as described in the README.md does not work:

$ docker-compose -f docker-compose.icessl.yml logs 
Attaching to orchestration_icessl_1
icessl_1  | python3: can't open file '/icessl/ice-ca-certs.py': [Errno 2] No such file or directory